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A 45-year-old man develops a large meningioma that compresses the brain. A head CT scan demonstrates a

subfalcine herniation. This herniation would most likely damage which of the following structures?

A. Cerebellar tonsils

B. Cingulate gyrus

C. Medial temporal lobe

D. Medulla

E. Midbrain

Explanation:

The correct answer is B. Brain herniation can occur either with generalized increased intracranial pressure or

as a consequence of a mass lesion of the cranium. Subfalcine herniation occurs when part of one cerebral

hemisphere herniates under the falx membrane, which separates the two cerebral hemispheres along the

midline of the skull. The gyrus most affected is the cingulate gyrus, which runs along the medial aspect of the

cerebral hemisphere, just above the corpus callosum.

The cerebellar tonsils (choice A) can herniate into the foramen magnum, in a tonsillar herniation. The medulla

(choice D) can be compressed by the herniating cerebellar tonsils, producing damage to this structure.

The medial temporal lobe (choice C) can be damaged in uncal herniation.

The midbrain (choice E) can be damaged in the course of a uncal herniation.

A 25-year-old woman in her 22nd week of pregnancy develops hypertension and mild proteinuria. Due to the

baby's gestational age, her obstetrician chooses to carefully monitor the mother for any sign of developing

complications rather than to immediately deliver the baby. Which of the following complications account for the

most maternal deaths in preeclampsia?

A. Cerebral edema and laryngeal edema

B. Cerebral hemorrhage and adult respiratory distress syndrome

C. Convulsions and renal tubular necrosis

D. Hemolysis and hepatic infection

E. Hepatic rupture and renal cortical necrosis

Explanation:

The correct answer is B. The disease is preeclampsia, which may be complicated by a wide variety of serious

conditions. Historically, the appearance of convulsions defined the transition from preeclampsia to eclampsia;

however the concept of eclampsia is probably flawed because many other serious complications can occur

even in the absence of seizures. Statistically, the most common causes of maternal death in preeclampsia are

cerebral hemorrhage and pulmonary complications, notably adult respiratory distress syndrome.

Cerebral edema and laryngeal edema (choice A), hemolysis and hepatic infarction (choice D), and hepatic

rupture and renal cortical necrosis (choice E) can all be complications of preeclampsia, but are not the most

common causes of maternal mortality.

Convulsions and renal tubular necrosis (choice C) can be complications of preeclampsia, but convulsions

indicate that eclampsia has developed.

Other complications of preeclampsia not listed in the answer choices include retinal detachment, cortical

blindness, pulmonary edema, disseminated intravascular coagulation, low platelet counts, and in the fetus,

brain damage and death from asphyxia.

A 4-year-old girl is brought to the clinic by concerned parents. Physical examination is remarkable for extremity

edema. Urinalysis shows significant proteinuria, but no red cells or casts. Electron microscopy performed on a

kidney biopsy would be most likely to show which of the following findings?

A. Dense deposits

B. Fusion of epithelial foot processes

C. Mesangial deposits

D. Subendothelial deposits

E. Subepithelial spikes

Explanation:

The correct answer is B. The most frequent cause of nephrotic syndrome in children is minimal change disease

(lipoid nephrosis), which is characterized by an absence of findings by light microscopy, and fusion of epithelial

foot processes by electron microscopy.

Dense deposits (choice A) are seen in type II membranoproliferative glomerulonephritis.

Mesangial deposits (choice C) are a prominent feature of IgA nephropathy and are seen to a lesser degree in

several other glomerulonephritides.

Subendothelial deposits (choice D) are seen in type I membranoproliferative glomerulonephritis.

Subepithelial spikes (choice E ) are a feature of membranous glomerulonephritis.

A young man presents for an employment physical. He is very tall, has long fingers, and hyperflexible joints. He

states that he has always been called "double jointed". Which of the following disorders is associated with this

syndrome?

A. Dissecting aortic aneurysm

B. Hepatosplenomegaly

C. Polycystic kidneys

D. Progressive neurologic dysfunction

E. Retinoblastoma

Explanation:

The correct answer is A. The patient has Marfan syndrome, an autosomal dominant disorder caused by a defect

in the gene on chromosome 15 encoding fibrillin, a 350 kD glycoprotein. Fibrillin is a major component of

elastin-associated microfibrils, which are common in large blood vessels and the suspensory ligaments of the

lens. Abnormal fibrillin predisposes for cystic medial necrosis of the aorta, which may be complicated by aortic

dissection. Other features of the syndrome are subluxated lens of the eye, mitral valve prolapse, and a

shortened life span (often due to aortic rupture).

A 55-year-old patient presents with chronic cough. Chest x-ray demonstrates a coin lesion near the apex of the

lung. CT-guided biopsy of the lesion demonstrates a malignant tumor arising in an area of scarred lung. Which of

the following type of cancer is most likely to be present?

A. Adenocarcinoma

B. Bronchioloalveolar carcinoma

C. Large cell carcinoma

D. Oat cell carcinoma

E. Squamous cell carcinoma

Explanation:

The correct answer is A. Tumors that arise peripherally and can cause coin lesions include adenocarcinoma

(choice A), bronchioloalveolar carcinoma (choice B), and large cell carcinoma (choice C). Of these,

adenocarcinoma is the form specifically associated with lung scarring related to old granulomatous disease, old

chronic obstructive lung disease, or other old damage to the lungs.

Remember bronchioloalveolar carcinoma (choice B) as the one that is not associated with smoking.

Large cell carcinoma (choice C) is an aggressive, undifferentiated form of lung cancer.

Remember oat cell (small cell, choice D) carcinoma as the one that can commonly cause paraneoplastic

syndromes such as SIADH and Cushing's syndrome.

You should associate squamous cell carcinoma of the lung (choice E) with hypercalcemia.

A patient undergoes total thyroidectomy for a mass lesion of the thyroid. During the surgery, the surgeon notes

that the parathyroid glands appeared enlarged. The thyroid lesion shows neuroendocrine-type cells and amyloid

deposition. This patient's thyroid and parathyroid lesions may be related to which of the following oncogenes?

A. bcl-2

B. C-myc

C. erb-B2

D. L-myc

E. ret

Explanation:

The correct answer is E. The thyroid lesion is medullary carcinoma of the thyroid. The coexistence of

parathyroid hyperplasia suggests Sipple's syndrome (MEN II). These patients also tend to develop

pheochromocytoma. Both MEN II and MEN III are associated with the ret oncogene.

Associate bcl-2 (choice A) with follicular and undifferentiated lymphomas.

Associate C-myc(choice B) with Burkitt's lymphoma.

Associate erb-B2 (choice C) with breast, ovarian, and gastric carcinomas.

Associate L-myc(choice D) with small cell carcinoma of the lung.

A 2-year-old child develops a localized cutaneous infection with phage group II Staphylococcus aureus. A rash

resembling the rash of scarlet fever begins around the mouth, then spreads to the trunk and extremities. A few

bullae develop, which burst, leaving denuded skin. At what level in the skin did these bullae most likely develop?

A. Across the basal cells

B. Below the basement membrane

C. Between the basal cells and the basement membrane

D. High in the epidermis

E. Just above the basal cells

Explanation:

The correct answer is D. Bullous diseases of the skin are subdivided on the basis of the level at which the

cleavage for blister formation occurs. In general, the lower in the epidermis/dermis that the cleavage plane

occurs, the more dangerous and widespread the blistering. This is because blistering at lower levels,

particularly those that damage or remove the basal cell layer, permits loss of substantial amounts of fluid and

heals slowly (often with significant scarring). Scalded-skin syndrome (toxic epidermal necrolysis), as seen in this

patient, may follow staphylococcal (often phage group II) skin infection. This disorder fortunately involves the

very superficial squamous cells just beneath the granular layer. Consequently, the disease (which typically

produces bright red skin sloughing, predominately in intertriginous regions) usually resolves without sequelae

after antibiotic therapy. "Scalded-skin" may also be observed in association with drug-induced erythema

multiforme. Major inciting agents include phenylbutazones, sulfonamides, and barbiturates. This form usually

affects the mucosa (eyes, mouth) first, and is much more dangerous because the blistering is subepidermal,

and the entire overlying epidermis becomes necrotic.

Exploratory laparotomy in a patient with an acute abdomen demonstrates a several-foot long loop of small

intestine with a dark red-to-brown, edematous appearance. The lesion ends abruptly on both the distal and

proximal edges. Which of the following diagnoses is suggested by this appearance?

A. Abetalipoproteinemia

B. Celiac sprue

C. Ischemic bowel disease

D. Tuberculosis

E. Whipple's disease

Explanation:

The correct answer is C. The question describes the typical appearance of a gangrenous small intestine. This

life-threatening condition can be due to arterial thrombosis, embolic arterial occlusion, venous thrombosis, or

mechanical strangulation of vessels in twisted bowel loops. Treatment is surgical removal of the involved

segment.

Abetalipoproteinemia (choice A), celiac sprue (choice B), and Whipple's disease (choice E) involve the mucosa

and submucosa, and would not be obvious at laparotomy.

Tuberculosis (choice D) tends to produce mass lesions and strictures.

A 55-year-old woman presents to her physician after several episodes of syncope. Physical examination is

remarkable for a low-pitched "plopping" sound during mid-systole. Two-dimensional echocardiography

demonstrates a ball-valve type obstruction of the mitral valve. Which of the following would most likely be

observed if the cause of the obstruction were biopsied?

A. Benign glandular tissue

B. Densely packed smooth muscle

C. Densely packed striated muscle

D. Malignant glandular tissue

E. Scattered mesenchymal cells in a myxoid background

Explanation:

The correct answer is E. The most common primary cardiac tumor of adults is atrial myxoma, which typically

occurs as a single lesion in the left atrium that may intermittently obstruct the mitral valve. Histologically, these

tumors are composed of scattered mesenchymal cells in a prominent myxoid background.

Benign glandular tissue (choice A) suggests an adenoma, which is not usually found in the heart.

Densely packed smooth muscle (choice B) suggests a leiomyoma, which is not usually found in the heart.

Densely packed striated muscle (choice C) suggests rhabdomyoma, which is the most common primary cardiac

tumor in children, not adults.

Malignant glandular tissue (choice D) suggests carcinoma, which can be metastatic to the heart, but does not

usually cause a ball-valve obstruction.

A 65-year-old man develops oliguria and peripheral edema over a period of weeks. Urinalysis reveals hematuria

and proteinuria; examination of the urinary sediment reveals red cell casts. Radiologic and ultrasound studies fail

to demonstrate an obstructive lesion. Renal biopsy shows many glomerular crescents. This presentation is most

suggestive of which of the following conditions?

A. Anti-glomerular basement membrane disease

B. Diabetic nephropathy

C. Hypertensive nephropathy

D. Lupus nephritis

E. Minimal change disease

Explanation:

The correct answer is A. The two principal causes of rapidly progressive glomerulonephritis are anti-glomerular

basement membrane (including both Goodpasture's syndrome and isolated anti-glomerular basement disease)

and primary systemic vasculitis (including Wegener's granulomatosis, microscopic polyarteritis, idiopathic

rapidly progressive glomerulonephritis, Churg-Strauss syndrome, polyarteritis nodosa, giant-cell arteritis, and

Takayasu's arteritis). A very large variety of other systemic and primary glomerular disease may occasionally

cause rapidly progressive glomerulonephritis, but this is usually not the typical presentation for these diseases.

Diabetic nephropathy (choice B) typically begins with microalbuminuria and hypertension and progresses over a

10 to 20 year period to renal failure.

Hypertensive nephropathy (choice C) due to essential hypertension typically presents with slowly rising BUN

and creatinine; hypertensive nephropathy due to malignant hypertension presents with more rapidly rising BUN

and creatinine.

Lupus nephritis (choice D) can have many presentations, but the most typical is proteinuria, which may be

severe enough to cause nephrotic syndrome. Also, 90% of cases of systemic lupus erythematosus occur in

women, usually of child-bearing age.

Minimal change disease (choice E) typically presents with nephrotic syndrome and is not consistently

associated with recognizable glomerular changes by light microscopy. Podocyte foot-process fusion can be

seen by electron microscopy.

A 57-year-old female with megaloblastic anemia is found to be deficient in vitamin B12. Levels of all other

essential vitamins are within normal limits. Further investigations confirm that she has pernicious anemia. Which

of the following gastrointestinal diseases is most likely to be associated with this condition?

A. Angiodysplasia

B. Atrophic gastritis

C. Duodenal ulcer

D. Menetrier's disease

E. Ulcerative colitis

Explanation:

The correct answer is B. An important cause of vitamin B12 deficiency is pernicious anemia, an autoimmune

disease associated with atrophic gastritis. In atrophic gastritis, the gastric epithelium undergoes intestinal

metaplasia, thereby replacing gastric chief and parietal cells with goblet cells. The metaplastic epithelium

produces insufficient intrinsic factor to bind the dietary vitamin B12. Megaloblastic anemia develops over a

number of years.

Angiodysplasia (choice A) is a disease of intermittent lower intestinal bleeding due to rupture of mucosal and

submucosal venules and capillaries under normal colonic wall tension. Angiodysplasia may produce iron

deficiency anemia.

Duodenal ulcers (choice C) may also produce iron deficiency anemia due to chronic blood loss. They are

caused by damage to the duodenal epithelium by gastric acids and are associated with cirrhosis, COPD,

chronic renal failure, and hyperparathyroidism.

Menetrier's disease (choice D) is also known as hypertrophic gastropathy. It is an idiopathic condition typified by

thickened gastric rugae and hyperplastic mucosa, producing a thickened gastric wall, hypochlorhydria,

epigastric distress, and protein-losing gastroenteropathy.

Ulcerative colitis (choice E) is an inflammatory bowel disease almost entirely restricted to the large intestine. It

usually causes intestinal distress and diarrhea, and it may produce a malabsorption syndrome that includes

vitamin B12 deficiency.

A 50-year-old man presents at an emergency room because of several hours of progressively increasing chest

pain that no longer responds to sublingual nitroglycerin. This type of angina is thought to be due to which of the

following conditions?

A. Atherosclerosis alone

B. Coronary artery embolism

C. Coronary artery spasm

D. Thrombosis with or without underlying atherosclerosis

E. Vasculitis

Explanation:

The correct answer is D. The patient has unstable or crescendo angina, which is thought to be due to a slowly

developing thrombosis in a coronary artery branch. The thrombosis may or may not occur over an area of the

vessel involved by atherosclerotic plaque. Thrombolytic agents are particularly helpful in this type of patient.

Atherosclerosis alone (choice A) usually causes stable angina occurring with exertion.

Coronary artery embolism (choice B) is uncommon, but can occur if a plaque at the aortic orifice fragments and

is driven into a coronary artery.

Coronary artery spasm (choice C) is thought to cause angina at rest (Prinzmetal's angina). This type of angina

is typically severe, but does not have a crescendo pattern, and often occurs in younger patients.

Coronary artery vasculitis (choice E) is important in the pathogenesis of Kawasaki's disease.

A 3-year-old boy is brought to the emergency department after the acute onset of headache, vomiting, nuchal

rigidity, and impaired mental status. MRI reveals a posterior fossa tumor that fills the 4th ventricle. Surgery is

immediately started, and intraoperative consultation leads to a "frozen section" diagnosis of medulloblastoma.

Which of the following pathologic mechanisms most likely accounts for this child's clinical presentation?

A. Acute hemorrhage into the 4th ventricle

B. Alteration of medullary function

C. Increased intracranial pressure

D. Infiltration of the cerebellar vermis by the neoplasm

E. Spread of tumor to the subarachnoid space

Explanation:

The correct answer is C. Any tumor "filling the 4th ventricle" blocks the circulation of cerebrospinal fluid (CSF).

This blockage leads to increased intracranial pressure, which manifests with nausea, vomiting, headache,

nuchal rigidity, and mental status changes. If surgery is not performed promptly, cerebellar tonsillar herniation

and rapid death will ensue. In children, medulloblastoma and ependymoma are the most frequent neoplasms

presenting in this manner.

There is no evidence in this case suggesting that acute hemorrhage into the 4th ventricular cavity (choice A)

has occurred, nor is medulloblastoma typically associated with this complication. CNS tumors that frequently

bleed are metastases from melanoma, renal cell carcinoma, and choriocarcinoma.

Alterations in medullary function (choice B) lead to cardiorespiratory instability and may be caused by direct

tumor compression or infiltration of the medulla, neither of which is supported by MRI findings in this case.

Infiltration of the cerebellar vermis (choice D) is certainly seen in many cases of medulloblastoma, a tumor that

arises from this midline cerebellar structure. However, this would lead to truncal ataxia and gait instability, not

symptoms of increased intracranial pressure.

Medulloblastoma characteristically spreads to the subarachnoid space (choice E), from which the neoplasm

may metastasize to distant sites such as spinal cord. Plaques of medulloblastoma are often found on the

cerebellar surface, creating a characteristic sugar coating, but this would not cause any significant blockage of

CSF circulation.

Biopsy of a 4 mm rough, tan, and slightly raised skin lesion on the face of a 65-year-old man demonstrates

atypical basal cells with eosinophilic cytoplasm but persistent intercellular bridges. The stratum corneum is

thickened and parakeratosis is present; the remainder of the epidermis is thinned. Which of the following features

would probably additionally be seen in the dermis?

A. Benign nevus cells

B. Blue-gray elastic fibers

C. Large numbers of spindle-shaped fibroblasts

D. Malignant nevus cells

E. Touton giant cells

Explanation:

The correct answer is B. The lesion described is an actinic keratosis, which is a common premalignant lesion

caused by solar damage, which also characteristically damages the elastic fibers (changing their color in

stained tissue to blue-gray) of the superficial dermis.

Benign nevocellular nevus cells (choice A) are found in common moles (nevocellular nevi).

Large numbers of spindle-shaped fibroblasts (choice C) are found in dermatofibromas.

Malignant nevus cells (choice D) are found in melanoma.

Touton giant cells (choice E) are found in xanthomas.

Following a difficult delivery accompanied by significant maternal hemorrhage, a new mother develops a severe

retro-orbital hemorrhage with nausea and vomiting. The patient then develops fever and visual field loss, followed

by impairment of medial and downward gaze accompanied by diplopia and ptosis. CT scan demonstrates

hemorrhage in the pituitary gland with extension to the meninges. Immediate therapy with which of the following

hormone combinations should be instituted?

A. Glucocorticoids and estrogens

B. Glucocorticoids and thyroid hormone

C. Growth hormone and estrogens

D. Mineralocorticoids and growth hormone

E. Prolactin and mineralocorticoids

Explanation:

The correct answer is B. Pituitary apoplexy, which is a life-threatening infarction of the pituitary gland, may

result after obstetric hemorrhage (Sheehan's syndrome), with increased intracranial pressure, or during

systemic anticoagulation therapy. While the patient may have a generalized hypofunction of the pituitary in

these settings, the most important hormones to quickly replace are glucocorticoids (synthesized by the adrenal

cortex under pituitary ACTH control) and thyroid hormone (under pituitary TSH control), since deficiency of

these hormones produces life-threatening syndromes.

Growth hormone, estrogens, and prolactin (choices A, C, D, and E) do not require immediate replacement.

Mineralocorticoids (choices D and E) can be replaced if diabetes insipidus develops.

A 45-year-old man from southern China is diagnosed with a nasopharyngeal tumor. Histologically, this neoplasm

is composed of anaplastic cells immunoreactive for cytokeratin admixed with abundant lymphocytes. Which of the

following factors is most likely implicated in the pathogenesis of this neoplasm?

A. Cigarette smoking

B. Epstein-Barr virus infection

C. Ionizing radiation

D. Overexpression of the bcl-2 gene

E. Trisomy 8

Explanation:

The correct answer is B. The neoplasm described here is known as lymphoepithelioma, an inappropriate

designation that emphasizes the histologic features of a lymphocyte-rich squamous cell carcinoma. This tumor,

AKA nasopharyngeal carcinoma, is the most frequent childhood malignancy in certain African regions and one

of the most frequent adult tumors in southern China. Epstein-Barr virus genome has been identified in most of

these neoplasms.

Cigarette smoking (choice A) is a risk factor for a number of malignant neoplasms, such as lung cancer. In the

upper respiratory tract, cigarette smoking is a strong predisposing factor for laryngeal carcinoma, but it has not

been linked to the pathogenesis of nasopharyngeal carcinoma.

Radiation injury (choice C) is a well-known risk factor for many human neoplasms, such as leukemia and thyroid

cancer, but not for nasopharyngeal carcinoma. Although any cell type is susceptible to neoplastic

transformation by radiation, there is a sort of hierarchy of vulnerability. The most frequent radiation-induced

cancers are leukemias and thyroid carcinoma, followed by breast, lung, and salivary gland tumors. Skin, bone,

and the gastrointestinal tract are least vulnerable to radiation carcinogenesis.

Overexpression of the bcl-2 gene (choice D) is found in most B-cell follicular lymphomas. bcl-2 is a member of a

large family of genes that regulate apoptosis. bcl-2 inhibits apoptosis, so that its overexpression allows

neoplastic lymphocytes to survive for long periods and accumulate progressively in lymph nodes and bone

marrow.

Trisomy 8 (choice E) has been identified in some cases of olfactory neuroblastoma, a malignant tumor of small

round cells arising from the olfactory mucosa and resembling adrenal neuroblastoma.

A 38-year-old man has a cold, then recovers. A few days later, he notices a reddish-brown discoloration to his

morning urine. He presents to a physician, who elicits a recent history of fatigue, abdominal pain, and headaches.

Physical examination reveals slight jaundice. A complete blood count (CBC) reveals a hematocrit of 34, with a

leukocyte count of 3000/mm3 and a platelet count of 120,000/mm3. A peripheral smear shows mild macrocytosis

and polychromasia. The reticulocyte count is 5%. A urine sample appears yellow and clear. Which of the following

is the most likely diagnosis?

A. Aplastic anemia

B. Crigler-Najjar syndrome, type I

C. Dubin-Johnson syndrome

D. Hereditary spherocytosis

E. Paroxysmal nocturnal hemoglobinuria

Explanation:

The correct answer is E. The patient most likely has paroxysmal nocturnal hemoglobinuria (PNH), which can

cause a striking hemoglobinuria with red-brown to black urine. The condition usually presents in adulthood, the

incidence peaking in middle age. The hemoglobinuria, if present, is typically intermittent, although the classic

rhythmic nocturnal pattern is actually observed in only a minority of patients. Hemosiderinuria is usually present.

PNH is an acquired red cell defect caused by defective synthesis of a glycosylphosphatidylinositol (GPI) anchor,

which is associated with somatic mutations in the PIG-A gene (located on the X chromosome). Decreased GPI

anchor synthesis results in decreased expression of GPI-anchored proteins (GPI-AP), including

complement-regulating proteins, on the cell membrane. The deficiency of GPI-APs causes the red cells to

become extraordinarily sensitive to lysis by complement. Factors that may trigger hemolysis include infection

(even with the common cold), menstruation, surgical procedures, exposure to cold, vaccines, and other types of

stress. The patients are prone to venous thrombosis (thought to result from inappropriate platelet activation),

which may be the cause of the abdominal pain frequently experienced in this group. Thrombosis and

thromboembolism are the most frequent immediate causes of death in PNH patients, with the intrahepatic veins

being a favorite site for thrombosis (producing Budd-Chiari syndrome). Other complications include pigment

gallstones (secondary to chronic hemolysis) and granulocytopenia, leading to frequent infections. The definitive

test for PNH is Ham's test, in which serum is acidified to activate the complement pathway, then added to PNH

red cells, resulting in lysis.

In aplastic anemia (choice A), the reticulocyte count would not be elevated. Also, the slight degree of

pancytopenia observed in this man would tend to rule out marrow aplasia.

Type I Crigler-Najjar syndrome (choice B) is a cause of severe unconjugated hyperbilirubinemia because of a

defect in hepatic bilirubin conjugation. It is usually fatal in the first year of life.

Dubin-Johnson syndrome (choice C) is a usually asymptomatic cause of jaundice, but is not associated with

hemolytic anemia.

In hereditary spherocytosis (choice D), spherocytes would be seen on the peripheral smear, and splenomegaly

is common.

A 30-year-old patient presents to a clinician because of intermittent, severe headaches accompanied by

perspiration, palpitations, and pallor. Blood pressure on the initial examination was within normal limits, but, when

the patient came in later with a headache, it was 180/135 mm Hg. Urinary vanillylmandelic acid (VMA) levels were

elevated. Roughly, what percentage of the tumors causing this pattern is malignant?

A. 1%

B. 10%

C. 50%

D. 90%

E. 99%

Explanation:

The correct answer is B. The tumor is a pheochromocytoma that intermittently secretes epinephrine and other

vasoactive amines, producing episodes of elevated blood pressure accompanied by headache. This is the

tumor to associate with the rule of the 10's: 10% malignant, 10% bilateral, 10% extra-adrenal, 10% calcify, 10%

occur in kids, and 10% are familial. It is also a favorite target on examinations, although the incidence is quite

low.

A 25-year-old woman complains of abdominal pain of rapid onset in the right lower quadrant. She subsequently

undergoes surgery for suspected acute appendicitis. At surgery, however, a tubal pregnancy is discovered. The

most frequent predisposing factor for this condition is

A. endometriosis

B. an intrauterine device

C. leiomyomas of the uterus

D. pelvic inflammatory disease

E. previous surgery

Explanation:

The correct answer is D. The great majority of ectopic pregnancies (90%) occur in the fallopian tubes. The

other sites are the ovaries, abdominal cavity, and the intrauterine segment of the fallopian tubes. Any condition

that leads to anatomical abnormalities of the uterus and fallopian tubes may predispose to ectopic pregnancy.

The most frequent of such conditions is pelvic inflammatory disease (PID), which is usually associated with

salpingitis. PID is a common infectious condition most frequently caused by Neisseria gonorrhoeae and

Chlamydia trachomatis, both sexually transmitted. Other cases are due to a polymicrobial population, including

staphylococci, streptococci, coliform bacteria, and Clostridium perfringens, acquired during abortion or delivery.

PID leads to acute purulent salpingitis. If this is untreated or inadequately treated, it progresses to

salpingo-oophoritis, tubal abscesses, pyosalpinx, or hydrosalpinx. Even milder cases may cause adhesions

within the tube or between the tube and the ovary that interfere with implantation of the ovum and result in tubal

pregnancy. All the remaining conditions listed above may also predispose to ectopic pregnancy.

Endometriosis (choice A) refers to the presence of endometrium in abnormal locations, such as the ovary,

uterine ligaments, rectovaginal pouch, and pelvic peritoneum. It is an important clinical condition manifesting

with pain, dysmenorrhea, and infertility. Scarring at endometriotic sites may cause peritubal adhesions and

ectopic pregnancy.

An intrauterine device (choice B) may also increase the risk of ectopic pregnancy, but the mechanism of action

is not clear.

Leiomyomas of the uterus (choice C) are the most frequent benign tumor in women. They develop from the

smooth muscle as well-circumscribed nodules within the uterine wall (intramural), in a subserosal or submucosal

location. Leiomyomas may cause significant distortion of the uterine wall and interfere with implantation,

increasing the risk of ectopic pregnancy.

Previous surgery (choice E) of any kind may create scars and peritubal adhesions, thus predisposing to ectopic

pregnancy.

A 22-year-old male with fatigue, recurrent fever, and enlarged cervical lymph nodes has numerous atypical

lymphocytes in his peripheral blood smear. A biopsy from the patient's enlarged node shows expansion of

lymphoid follicles with preservation of the underlying architecture. Numerous atypical lymphocytes are present in

the paracortical areas. This patient most likely has

A. AIDS

B. Burkitt's lymphoma

C. Hodgkin's Disease

D. mononucleosis

E. non-Hodgkin's lymphoma

Explanation:

The correct answer is D. Infectious mononucleosis is a benign infection caused by the Epstein-Barr Virus (EBV),

a herpesvirus. Although B lymphocytes are infected by the virus, the characteristic atypical cells are activated

suppresser T cells - thus the paracortical location (T cell zone) in the lymph node. Lymph nodes in viral

infections show expansion of germinal centers without loss of normal architecture. All lymphomas, including

Burkitt's, Hodgkin's and non-Hodgkin's lymphomas, destroy the normal architecture of the lymph node.

Burkitt's lymphoma (choice B) produces a sea of monotonous, mitotically active cells in a "starry sky"

appearance.

Other non-Hodgkin's lymphomas (choice E) show either a nodular appearance or diffuse sheets of cells which

replace the germinal centers.

Hodgkin's lymphoma (choice C) also can show nodular or diffuse patterns, but is characterized by the presence

of Reed-Sternberg cells.

AIDS (choice A) is associated with a number of neoplastic and infectious processes that may alter the lymph

node structure. The characteristic lymph node changes in AIDS are progressive transformation of the germinal

centers, not paracortical hyperplasia.

A liver biopsy from a 54-year-old man shows many Mallory bodies. This finding is most suggestive of which of the

following diseases?

A. Alcohol abuse

B. Alpha1-antitrypsin deficiency

C. Hepatitis A

D. Hepatitis B

E. Wilson's disease

Explanation:

The correct answer is A. Mallory bodies are eosinophilic cytoplasmic inclusions ("alcoholic hyaline") that are

found in the largest numbers in alcoholic hepatitis. They were originally considered to be pathognomic of

alcohol abuse, but have since been found (in much smaller numbers) in many other liver conditions.

Alpha1-antitrypsin deficiency (choice B) involvement of the liver is characterized by periodic acid Schiff

(PAS)-positive cytoplasmic granules in hepatocytes.

Hepatitis A (choice C) and hepatitis B (choice D) infections are definitively established with serologic markers.

In Wilson's disease (choice E), there is excess copper deposition in the liver.

A 17-year-old boy has been taken to the emergency room three times for acute abdominal pain, but was

released each time without a definitive diagnosis. The frustrated emergency room physicians now consider him to

be "crazy," and have labeled him as having "irritable bowel syndrome." On the fourth occasion, he is brought in

passing stool-contaminated urine and a fistula is demonstrated between the small intestine and bladder. Which

of the following diseases would be most likely to cause this clinical scenario?

A. Celiac disease

B. Crohn's disease

C. Diverticulitis

D. Ulcerative colitis

E. Whipple's disease

Explanation:

The correct answer is B. Patients with gastrointestinal disease of a number of types have unfortunately had the

experience of "not being believed" when they complained to physicians about their problems. Both Crohn's

disease and ulcerative colitis (choice D) can present with abdominal pain, however the presence of a enteric

fistula favors the diagnosis of Crohn's. Fistulae can occur with Crohn's disease because the inflammatory

process involves the entire bowel wall, in contrast to the mucosal involvement in ulcerative colitis.

The distinctive feature of celiac disease (choice A) is malabsorption due to gluten sensitivity. The

malabsorption generally improves promptly with removal of gluten from the diet.

Diverticulitis (choice C) can present with abdominal pain and fever, but is usually a disease of older adults.

Whipple's disease (choice E) is a small intestinal malabsorption syndrome that has been related to microbial

infection (macrophages can be seen containing bacilliform bodies that have been identified as Tropheryma

whippellii ).

Before being approved by the FDA, a chemical is tested for carcinogenicity by examining its mutagenic effects on

bacterial cells in culture. Which of the following tests is used to make this determination?

A. Ames test

B. Nitroblue tetrazolium test

C. Watson-Schwartz test

D. Widal test

E. Woellner enzyme test

Explanation:

The correct answer is A. The test described is the Ames test, which measures damage to DNA and correlates

well with carcinogenicity in vitro. It is relatively inexpensive to perform, compared to other tests of

carcinogenicity, and is frequently used as a screening test for potential carcinogens.

The nitroblue tetrazolium test (choice B) is used to examine the ability of neutrophils to undergo a respiratory

burst, and is used in the diagnosis of hereditary immunodeficiencies.

The Watson-Schwartz test (choice C) detects porphobilinogen in urine, and is used in the diagnosis of

porphyrias.

The Widal test (choice D) is used to diagnose typhoid fever.

The Woellner enzyme test (choice E) detects heterophil antibodies in patients with Epstein-Barr virus infection,

such as infectious mononucleosis.

A 35-year-old sailor from a merchant ship that has been cruising the Caribbean presents to a clinician because of

painful, flocculent masses in his groin. Physical examination demonstrates multiple enlarged, abscessed lymph

nodes draining through the skin via indolent sinuses. The sailor describes previously having a small papular

lesion on his penis that spontaneously resolved. Which of the following is the most likely diagnosis?

A. Condyloma acuminatum

B. Granuloma inguinale

C. Herpes virus infection

D. Lymphogranuloma venereum

E. Syphilis

Explanation:

The correct answer is D. This is lymphogranuloma venereum. The enlarged, abscessed lymph nodes are

termed “buboes” (which can also occur in bubonic plague). The only other commonly discussed

sexually transmitted disease in which they can occur is chancroid. Histologically, the buboes of

lymphogranuloma venereum are enlarged lymph nodes with stellate abscesses. The primary lesion is usually a

self-healing papule or shallow ulcer. The causative organism is Chlamydia trachomatis.

Condyloma acuminatum (choice A) causes a papillary lesion and does not cause buboes.

Granuloma inguinale (choice B) causes a spreading ulcer and does not cause buboes.

Herpes virus infection (choice C) causes tiny vesicles and ulcers and does not cause buboes.

Syphilis (choice E) causes a painless nodule and does not cause buboes.

A 17-year-old woman notices that her urine becomes red after she is given sulfonamides for treatment of a

urinary tract infection. Both urine and serum test positive for free hemoglobin, and the urine red cell count is 1.2

million/mm3. A peripheral blood smear shows normocytic and normochromic red cells and a few "bite cells."

Deficiency of which of the following substances is most likely responsible for these symptoms?

A. Alpha-chain of hemoglobin

B. Beta-chain of hemoglobin

C. Glucose-6-phosphate dehydrogenase

D. Glycoprotein IIb/IIIa

E. Spectrin

Explanation:

The correct answer is C. The presence of free hemoglobin in the serum and urine, and "bite cells" due to splenic

removal of Heinz bodies (oxidized hemoglobin) all point to hemolysis. Hemolysis following oxidant injury by drugs

(sulfonamides, for example) or infection suggests glucose-6-phosphate dehydrogenase deficiency or the related

deficiencies of glutathione synthetase, pyruvate kinase, and hexokinase. These conditions are typically

asymptomatic between episodes of hemolysis.

Deficiencies of the alpha (choice A) and beta (choice B) chains of hemoglobin produce alpha and beta

thalassemia, respectively.

Deficiencies of glycoprotein IIb/IIIa (choice D) produce thrombasthenia, a platelet aggregation defect.

Deficiencies of spectrin (choice E) produce hereditary spherocytosis, characterized by hemolytic anemia and

splenomegaly.

A 27-year-old man presents to a physician because he was not able to feel a burn that he had sustained on the

stove burner. Neurologic studies demonstrate bilateral loss of pain and temperature sensation in the upper

extremities with preservation of touch sensation. No motor abnormalities are observed. This patient's condition

has been most frequently associated with which of the following?

A. Arnold-Chiari malformation

B. Broca's aphasia

C. Horner's syndrome

D. Tabes dorsalis

E. Wernicke's encephalopathy

Explanation:

The correct answer is A. The patient most probably has syringomyelia, in which softening and cavitation around

the central canal of the spinal cord damages crossing fibers of the spinothalamic tract with resulting bilateral

loss of pain and temperature (but not touch) sensation in the upper extremities. Many of the patients with

syringomyelia have Arnold-Chiari malformation, in which there is a congenital protrusion of the cerebellum and

medulla through the foramen magnum.

Broca's aphasia (choice B) is a nonfluent aphasia due to damage to the inferior frontal gyrus.

Horner's syndrome (choice C) is due to damage to the sympathetic innervation of the face, with resulting ptosis,

miosis, and anhidrosis.

Tabes dorsalis (choice D) is a degeneration of the dorsal columns and dorsal roots of the spinal cord due to

tertiary syphilis, producing impaired proprioception and locomotor ataxia.

Wernicke's encephalopathy (choice E) is a form of psychosis seen in alcoholics with vitamin B1 (thiamine)

deficiency.

A 5-year-old boy with a one month history of fevers and lassitude is found to have severe anemia, moderate

thrombocytopenia, and a white blood count of 12,000 cells per mm3. A bone marrow biopsy would most likely

reveal

A. acute lymphoblastic leukemia

B. acute myeloblastic leukemia

C. chronic lymphocytic leukemia

D. chronic myeloid leukemia

E. hairy cell leukemia

Explanation:

The correct answer is A. Acute lymphoblastic leukemia (ALL) is primarily a disease of children, with peak

incidence at 4 years of age. Approximately 80% of childhood leukemias are of the ALL type. Other features in

this scenario which further support an acute leukemia are fevers and anemia without marked elevations of the

white blood cell count.

Acute myeloblastic leukemia (AML; choice B) would present itself in a similar fashion - acute symptoms and

anemia with thrombocytopenia. Bone marrow biopsy is needed to definitively differentiate ALL and AML, but

AML represents only 20% of childhood leukemias. AML is primarily a disease of adolescents and young adults.

The chronic leukemias (choices C and D) are diseases of adulthood which present with nonspecific symptoms,

and are typically diagnosed when white counts are markedly elevated. Chronic myeloid leukemia (choice D), a

neoplasm of a pluripotent stem cell, also may present with thrombocytosis, rather than thrombocytopenia.

Hairy cell leukemia (choice E) is a relatively rare leukemia of older males. It infiltrates the spleen early in its

course and tends to present with pancytopenia due to bone marrow failure and splenic sequestration.

A lymph node biopsy from a patient with massively enlarged mediastinal nodes demonstrates multiple lacunar

cells. A few questionable classic Reed-Sternberg cells are found. This pattern is most consistent with which of the

following disorders?

A. Burkitt's lymphoma

B. Mixed cellularity Hodgkin's disease

C. Nodular sclerosing Hodgkin's disease

D. Normal lymph node

E. Predominately small cleaved cell lymphoma

Explanation:

The correct answer is C. Lacunar cells specifically suggest the nodular sclerosing variant of Hodgkin's disease.

Broad collagen bands should also be seen in the biopsy. The actual tumor cell in this lesion is the lacunar cell,

and classic Reed-Sternberg cells are difficult to find.

In Burkitt's lymphoma (choice A), sheets of small lymphocytes are interspersed with larger histiocytes,

producing a "starry sky" pattern.

In mixed cellularity Hodgkin's disease (choice B), classic Reed-Sternberg cells are plentiful.

Lacunar cells would not be seen in a normal lymph node (choice D) or in predominately small cleaved cell

lymphoma (choice E), a non-Hodgkin's lymphoma.

A 49-year-old African-American female with shortness of breath is found to have hilar lymphadenopathy on chest

x-ray. Biopsy of one of the lymph nodes reveals granulomas, and is highly suggestive of sarcoidosis. Which of

the following histological findings must have been present in the biopsy material to support the diagnosis of

granulomatous inflammation?

A. Asteroid bodies

B. Caseous necrosis

C. Epithelioid histiocytes

D. Fibroblast proliferation

E. Multinucleated giant cells

Explanation:

The correct answer is C. A granuloma is defined as a focus of chronic inflammatory reaction in which the

predominant cell type is the epithelioid macrophage or histiocyte. Epithelioid histiocytes are recognized on

standard H&E preparation by their pale pink cytoplasm and indistinct cell boundaries. Granulomas are

generally surrounded by a ring of lymphocytes and infrequent plasma cells. None of the other features are

required for the diagnosis of granulomas, although they may be present.

The granulomas of sarcoidosis usually contain many multinucleated giant cells, and frequently these giant cells

contain stellate inclusions called asteroid bodies. Neither asteroid bodies (choice A) nor giant cells (choice E)

are required to make the diagnosis of sarcoidosis, nor does their absence preclude the diagnosis.

Caseous necrosis (choice B) describes the gross appearance of cheesy, necrotic debris filling a nodule of

active tuberculosis, but also has come to describe its characteristic amorphous and eosinophilic appearance on

H&E sections. Caseous necrosis is suggestive of tuberculosis, not sarcoidosis.

Over time, fibroblasts proliferate (choice D) within the core of old, inactive granulomas, eradicating the

histiocytes and stereotypical appearance and producing a dense collagenous scar. This feature is not required

for the diagnosis of granulomas.

A patient's abdomen becomes distended with loculated masses of semi-translucent mucinous material produced

by a mucinous cystadenoma. Which of the following are the most likely sites for the primary tumor?

A. Colon or spleen

B. Liver or pancreas

C. Lung or bladder

D. Ovary or appendix

E. Prostate or gall bladder

Explanation:

The correct answer is D. This rare, but dramatic, condition is called pseudomyxoma peritonei, and is produced

when a malignant or benign (spread by rupture into the peritoneal cavity rather than true metastasis) mucus

producing tumor (mucinous cystadenoma or mucinous cystadenocarcinoma) produces gel-like mucus that fills

the peritoneal cavity. The usual sites of origin of these tumors are ovary and appendix. The condition, even

when benign, is difficult to treat because the mucus producing cells are spread all over the peritoneal lining,

and cannot be effectively removed. Home parenteral nutrition may be necessary as the gut (particularly

peristalsis) just does not function well in a sea of Jell-O that slowly becomes replaced with fibrous tissue bands.

A medical student examining a patient is startled when he cannot "find" the patient's heart during auscultation.

The patient laughs and tells him to "try the other side." Auscultation on the right side of the chest does

demonstrates an apparently normal heart beat. Further physical examination demonstrates that the liver edge

can be palpated on the left but not the right side of the abdomen. Questioning of the patient about his medical

history reveals a history of bronchiectasis and sinusitis. Which of the following should be suspected?

A. Down syndrome

B. Kartagener syndrome

C. Kawasaki disease

D. Marfan syndrome

E. Turner syndrome

Explanation:

The correct answer is B. Inversion of the heart, so that the morphologic left ventricle is in the right chest, is

called dextrocardia. Isolated dextrocardia is almost always associated with cardiac defects that may include

transposition of the atria and transposition of the great arteries. However, dextrocardia as part of situs inversus

totalis, with reversal of the thoracic and abdominal organs, is usually associated with a physiologically normal

heart. The cluster of situs inversus, sinusitis, and bronchiectasis is called Kartagener syndrome, which is

caused by defective ciliary function. Since migration of some embryonic cells during development appears to

be dependent on ciliary function, this is thought to explain the situs inversus.

You should associate Down syndrome (choice A) with an ostium primum type of atrial septal defect.

You should associate Kawasaki disease (choice C) with coronary artery aneurysms.

You should associate Marfan syndrome (choice D) with aortic dissection.

You should associate Turner syndrome (choice E) with coarctation of the aorta.

A 9-year-old boy complains of sudden severe pain in his left hip. There is no history of trauma. He says that he

had a "cold" for a few days. An x-ray film obtained at the local emergency department shows an "Erlenmeyer flask

shaped" distal femur. The medullary bone is hazy. There is osteosclerotic new bone formation, as well as areas of

corticomedullary osteonecrosis. Other members of his family have been known to have bone pain. Which of the

following findings would a biopsy of the marrow of the femur likely reveal?

A. Abnormal osteoclasts and mosaic lamellar bone

B. Accumulation of abnormal macrophages

C. Benign reactive bone around an osteoid nidus

D. Malignant sarcoma

E. Well-differentiated cartilage

Explanation:

The correct answer is B. The patient described above has Gaucher disease, a hereditary disease that affects

bones and other organs. Glucocerebrosides accumulate within macrophages in places such as bone marrow.

The failure of proper bone remodeling of the distal femur gives the characteristic "Erlenmeyer flask" shape on

x-ray. These patients suffer Gaucher crises from acute ischemia to the bone, usually in the pelvis and femoral

head. The pain is sudden, severe, and progressive, lasting 2 or more weeks before fading. The crisis usually

follows viral illness. Other findings include osteosclerotic bone and corticomedullary osteonecrosis.

Abnormal osteoclasts and mosaic lamellar bone (choice A) describe Paget disease of bone. This is a disease of

disordered bone remodeling that affects people older than 60. Although the etiology is unknown, it may be due

to viral effect on osteoclasts. The osteoclast activity is excessive, and increased absorption occurs. The

osteoclasts appear to have too many nuclei. The lamellar bone slowly acquires a mosaic pattern because of

irregular cement lines. Pain is usually due to fractures of the misshapen bone.

Benign reactive bone around an osteoid nidus (choice C) describes osteoid osteoma. This is a common lesion

that is found in young people aged 5-25 years. It is usually seen radiographically in the cortex of the diaphysis

as a small, round lesion, composed of a nidus of osteoid surrounded by woven bone. It is painful, usually at

night; the pain is relieved by aspirin. Surgery is curative.

Malignant sarcoma (choice D) would probably represent an osteosarcoma in this age and location. Clinically,

sarcomas do not present with acute pain, but rather are associated with steadily progressive pain. Radiographs

show a destructive tumor with elevated periosteum and reactive new bone formation. Treatment includes

amputation.

Well-differentiated cartilage (choice E), if located in the marrow space and not just caused by a misguided

biopsy attempt, would indicate a solitary chondroma or enchondroma. This is a benign tumor that is probably

hamartomatous in nature. It is asymptomatic and forms during development. It is sometimes found incidentally.

A 10-year-old boy is in a fire and sustains burns over 25% of his body. The next day, his serum urea nitrogen

(BUN) is 30 mg/dL and his serum creatinine is 0.8 mg/dL. He receives intravenous fluids throughout his course

and never has a significant drop in blood pressure or urine output. Which of the following most likely accounts for

his BUN and creatinine values?

A. Decreased renal perfusion

B. Distal urinary tract obstruction

C. Increased synthesis of urea

D. Renal glomerular disease

E. Renal tubule interstitial disease

Explanation:

The correct answer is C. This patient has elevated BUN and normal serum creatinine. Raised BUN with normal

creatinine can be seen in prerenal causes of azotemia, which can be subclassified into those due to decreased

perfusion of the kidney and those due to increased synthesis of urea. In this case, the boy's blood pressure

and urine output were maintained, so inadequate renal perfusion is unlikely. The burns themselves can cause

significant urea production, since urea is the major nitrogen-containing end product of protein catabolism, which

increases markedly in burn victims.

Decreased renal perfusion (choice A) also produces increased BUN with normal serum creatinine, but you

would expect to see urine output decrease as a consequence of the inadequate perfusion.

Distal urinary tract obstruction (choice B), due to processes such as stones, cancer, or benign prostatic

hyperplasia, causes both BUN and serum creatinine to rise, but the rise in serum urea is proportionally higher

than that of serum creatinine.

In renal glomerular disease (choice D) of sufficient severity to cause acute or chronic renal failure, creatinine

and urea usually rise in parallel.

In renal tubulointerstitial disease (choice E), notably in acute tubular necrosis, creatinine may rise

disproportionately to urea.

A 22-year-old male presents with complaints of dull lower back pain and morning stiffness. The pain was initially

episodic, but now has become persistent and bilateral. On physical examination, there is tenderness over the

costosternal junctions, spinous processes of the vertebrae, and the iliac crests. Which of the following tests would

be most likely to be helpful in establishing a diagnosis of ankylosing spondylitis?

A. C-reactive protein

B. Erythrocyte sedimentation rate

C. HLA typing

D. Serum alkaline phosphatase

E. Serum IgA

Explanation:

The correct answer is C. Ankylosing spondylitis is one of the spondyloarthropathies. It is a chronic inflammatory

joint disease primarily affecting the vertebrae and the sacroiliac joints, usually beginning in late adolescence or

early adulthood. Close to 90% of Caucasian patients with ankylosing spondylitis are HLA-B27 positive, so tests

for this HLA type are the most helpful of those listed in establishing the diagnosis.

C-reactive protein (choice A) and erythrocyte sedimentation rate (choice B) are non-specific markers of

inflammation that can be elevated in active ankylosing spondylitis.

Serum alkaline phosphatase (choice D) and serum IgA (choice E) can also be (usually mildly) elevated, but do

not specifically suggest ankylosing spondylitis.

A renal pathologist examining the day's kidney biopsies notes that one biopsy shows amorphous red nodules

within the glomerular mesangium in hematoxylin and eosin stained material. Congo red stain of the biopsy

demonstrates apple-green birefringence of these nodules. These nodules are most likely to be related to which

of the following?

A. Acute urinary tract infection

B. Diabetes mellitus

C. Sarcoidosis

D. Systemic lupus erythematosus

E. Tuberculosis

Explanation:

The correct answer is E. Glomerular nodules may be either the Kimmelstiel-Wilson nodules of diabetes mellitus

or may be composed of amyloid. An amyloid origin can be confirmed by staining with Congo red, which causes

the nodules to stain red with ordinary light but exhibit a distinctive "apple-green" birefringence when viewed with

polarized light. The most common type of amyloid (type AA) is due to deposition of altered immunoglobulin light

chains and is seen in diseases with chronic antigenic stimulation, such as tuberculosis.

Acute urinary tract infection (choice A) is an infection of too short a duration to cause amyloidosis.

Diabetic mellitus (choice B) is associated with glomerular nodules called Kimmelstiel-Wilson nodules, but these

will not show apple-green birefringence when viewed with polarized light.

Sarcoidosis (choice C) typically involves the lymph nodes, lungs, spleen, and to a lesser extent, the skin and

eye. It is unrelated to amyloidosis.

Systemic lupus erythematosus (choice D) can produce a wide range of renal lesions, but amyloid nodules are

not among the likely manifestations.

A microbiology laboratory reports growth of Staphylococcus aureus from pus drained from a breast abscess.

What is the most likely condition predisposing the patient to the development of a breast abscess?

A. Breast feeding

B. Endocarditis

C. Inflammatory breast carcinoma

D. Menopause

E. Paget's disease of the breast

Explanation:

The correct answer is A. Acute mastitis, frequently complicated by breast abscess formation, typically develops

in the postpartum period, when the nipples are first subjected to the physical stresses of breast feeding.

Bacteria enter the breast via cracks in the nipple, and flourish in the microenvironment of the lactating breast.

Acute mastitis causes redness, pain, and swelling in the affected breast; Staph. aureus is the most common

pathogen.

Although endocarditis (choice B) could send septic emboli to the breast, Staph. aureus endocarditis is more

commonly associated with bacteremia and fevers, proliferative glomerulonephritis, valvular dysfunction, and

emboli to the brain, kidneys, heart, and gut.

Inflammatory breast carcinoma (choice C) does not invoke an inflammatory response, and it is not associated

with an infection. Inflammatory breast carcinoma is characterized by tumor spread into the dermal lymphatics,

producing diffuse induration and skin tenderness with the typical peau d'orange appearance.

Mastitis arising in the perimenopausal period (choice D) is usually a chronic mastitis, caused by obstruction of

ducts due to inspissated secretions. Chronic mastitis is sterile. The breast tissue shows lymphocytes and

plasma cells surrounding dilated ducts filled by cellular debris.

Paget's disease (choice E) presents as skin changes on the breast or nipple, in association with ductal

carcinoma in the underlying breast that is percolating out into the epidermis. Paget's disease produces a

eczematous skin lesion that may be crusted or weeping, but it is not related to bacterial infection.

A patient complains to a physician of epigastric pain that fails to respond to antacids. Endoscopy demonstrates

an ulcerated mass on the greater curvature of the stomach. Genetic studies on the tumor demonstrate an

altered DCC gene. Which of the following tumor suppressor genes is found on the same chromosome as DCC?

A. BRCA-1

B. DPC

C. NF-1

D. NF-2

E. p53

Explanation:

The correct answer is B. The tumor is gastric carcinoma, which is associated with the DCC oncogene located

on the long arm of chromosome 18 (18q). DCC is also associated with carcinomas of colon. 18q also has the

DPC gene, associated with pancreatic cancer.

The BRCA-1 gene (choice A), associated with breast cancer and ovarian cancer, is on 17q.

The NF-1 gene (choice C), associated with neurofibromatosis type I, is on 17q.

The NF-2 gene (choice D), associated with neurofibromatosis type II, is on 22q.

The p53 gene (choice E), associated with many cancers, is on 17p.

A patient is brought to the emergency room following a seizure. Serum electrolyte studies demonstrate serum

sodium of 128 mEq/L. The urine osmolarity is higher than the serum osmolarity. Chest x-ray demonstrates a lung

mass. Which of the following forms of lung cancer is most likely to cause the described electrolyte imbalance?

A. Adenocarcinoma

B. Bronchioloalveolar carcinoma

C. Large cell carcinoma

D. Small cell carcinoma

E. Squamous cell carcinoma

Explanation:

The correct answer is D. The patient has SIADH (syndrome of inappropriate antidiuretic hormone secretion),

which can be caused by ectopic ADH secretion by small cell carcinomas of the lung, CNS disorders, chronic

pulmonary disease, and certain drugs. Features of SIADH include excessive water retention, hyponatremia

(which can lead to seizures when severe), and serum hypo-osmolarity with urine osmolarity greater than serum

osmolarity.

Associate adenocarcinoma (choice A) with peripheral lung cancer and lung cancer arising in scars.

Associate bronchioloalveolar carcinoma (choice B) with alveolar-like spaces and no link to smoking.

Large cell carcinoma (choice C) is an aggressive, undifferentiated lung neoplasm.

Associate squamous cell carcinoma (choice E) with bronchogenic origin, a strong association with smoking, and

hypercalcemia.

Examination of a skin lesion demonstrates very abnormal squamous cells with a high nuclear/cytoplasmic ratio

and clumped chromatin. These cells form nests within the epidermis that extend to the superficial surface of the

epithelium. In some places, nests of these cells have central areas of abnormal keratin formation. The basement

membrane is intact and no nests of cells are seen in the dermis. Which of the following terms best describes this

lesion?

A. Carcinoma in situ

B. Dysplasia

C. Invasive carcinoma

D. Metaplasia

E. Metastatic carcinoma

Explanation:

The correct answer is A. The lesion is an example of carcinoma in situ. The presence of keratin pearls and the

distribution of abnormal cells all the way to the top of the epidermis distinguish this lesion from simple dysplasia

(choice B), in which abnormal cells are seen only in the lowermost layers of the epidermis.

Invasive carcinoma (choice C) would be indicated by a disruption of the basement membrane or the presence

of nests of cells in the dermis.

The term metaplasia (choice D) is used when a normal epithelium is replaced by another mature, differentiated

epithelium.

Tumor cells in lymphatics or blood vessels would suggest progression to metastatic carcinoma (choice E).

Which of the following forms of ischemic heart disease manifests with slowly progressive heart failure, with or

without other clinical manifestations of myocardial ischemia?

A. Chronic ischemic heart disease

B. Myocardial infarction

C. Prinzmetal angina

D. Stable angina

E. Unstable angina

Explanation:

The correct answer is A. Atherosclerosis of coronary arteries is the underlying pathologic change in the great

majority of cases of ischemic heart disease. Ischemic heart disease may manifest with several clinical

syndromes depending on distribution and morphology of atherosclerotic changes and rate of progression. A

slowly progressive increase in luminal stenosis in all major coronary vessels results in diffuse ischemia of the

myocardium and dropout of scattered myocytes throughout the ventricular walls. Eventually, such a reduction

in myocardial mass will lead to decreased contractility and heart failure. Patients with this chronic ischemic

heart disease often come to clinical attention with signs and symptoms of congestive heart failure, sometimes

without any history of chest pain or arrhythmias.

Myocardial infarction (choice B) may be clinically silent (ie, without pain), although it is usually associated with

severe chest pain. If the infarct is extensive, cardiogenic shock ensues.

All forms of angina can be easily ruled out as correct choices since angina indicates, by definition, paroxysmal

chest pain due to reversible myocardial ischemia. Prinzmetal angina (choice C) is an uncommon form of angina

occurring at rest and caused by vasospasm. Stable angina (choice D) refers to chest pain with a predictable

pattern of onset, usually after physical efforts, emotional excitement, or any cause of increased cardiac load.

Unstable angina (choice E) manifests with chest pain in an unpredictable, inconstant pattern, often at rest and

with progressively increasing frequency. Stable angina is associated with fixed narrowing of coronary arteries

due to stable plaques; unstable angina results from disrupted atherosclerotic plaques. Disrupted plaques lead

to abrupt worsening of luminal stenosis by promoting formation of small platelet aggregates or producing small

microscopic atheroemboli. Unstable angina is a harbinger of myocardial infarction.

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