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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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