Módulo 1 Med. Interna Flashcards
A 23-year-old woman comes to the physician for a health maintenance examination. She enjoys good health and exercises regularly. Her height is 172 cm (68 in) and weight is 66 kg (145 lb). Her blood pressure is 120/80 mm Hg, pulse is 74/min, and respirations are 12/min. Physical examination is unremarkable except for heart auscultation, which reveals an isolated midsystolic click. Which of the following is the most common cause of this auscultatory finding?
(A) Bicuspid aortic valve
(B) Congenital pulmonary stenosis
(C) Mitral valve prolapse
(D) Ruptured papillary muscle
(E) Tricuspid regurgitation
Respuesta: C
The correct answer is C. The most characteristic manifestation of a floppy mitral valve is a midsystolic click. This frequently asymptomatic condition may be associated with chest pain, dyspnea, palpitations, and other nonspecific symptoms. Patients with a midsystolic click as the only sign are usually asymptomatic; however, those with a systolic murmur may have hemodynamically significant mitral valve regurgitation. In addition, mitral valve prolapse is associated with an increased incidence of infective endocarditis, arrhythmias, sudden death, and cerebral embolism.
Bicuspid aortic valve (choice A) is the most frequent type of congenital defect of the aortic valve. It may manifest with valvular stenosis, giving rise to a systolic murmur sometimes associated with an opening click.
Congenital pulmonary stenosis (choice B) is a rare condition that gives auscultatory signs similar to aortic stenosis, i.e., a harsh systolic click sometimes associated with an opening click.
A ruptured papillary muscle (choice D) may develop as a complication of infective endocarditis or myocardial infarction. It may lead to mitral or tricuspid regurgitation and thus manifest with a systolic murmur not associated with clicks.
Tricuspid regurgitation (choice E) manifests with a harsh systolic murmur that increases in intensity during inspiration. The most common cause is right ventricular overload; less common causes are infective endocarditis and right ventricular myocardial infarction.
A 50-year-old man comes to the physician because of gingival bleeding, epistaxis, and fever for 2 days. He appears acutely ill. His temperature is 39 C (102 F), blood pressure is 120/70 mm Hg, pulse is 120/min, and respirations are 22/min. Bilateral rhonchi are heard on chest examination. He is admitted for further evaluation. Chest x- ray shows bibasilar infiltrates consistent with bronchopneumonia. Blood tests show 12,000 leukocytes/mm3 with numerous myeloid blasts. Platelet count is 15,000/mm3. A bone marrow biopsy demonstrates hypercellular marrow, with 35% blasts. Elongated cytoplasmic inclusions consistent with Auer rods are appreciated in peripheral and marrow blasts. Which of the following is the most likely diagnosis?
(A) Acute lymphocytic leukemia (ALL)
(B) Acute myelogenous leukemia (AML) (C) Chronic myelogenous leukemia (CML)
(D) Leukemoid reaction
(E) Myelodysplastic
Respuesta: B
The correct answer is B. The clinical manifestations are consistent with acute myelogenous leukemia (AML). This disease of middle- aged people (median age at presentation is 50 years) is due to neoplastic transformation of a bone marrow stem cell that is incapable of differentiating into mature leukocytes. A large number of blasts invade the bone marrow and the peripheral blood. AML is subdivided into seven types with different prognostic and therapeutic implications. These types are determined on the basis of the degree of maturation of blasts, their morphology, and coexisting cytogenetic abnormalities. Leukocytosis may be mild or even absent (“aleukemic leukemia”). However, most of the circulating leukocytes are blasts or immature myeloid forms. Signs and symptoms result from neutropenia, anemia, and thrombocytopenia. Auer rods consist of eosinophilic, needle-like inclusions in myeloid cells and are pathognomonic of AML.
In contrast to AML, acute lymphocytic leukemia (ALL; choice A) is a disease of children, with a peak of incidence from 3 to 7 years. ALL represents 80% of all cases of acute leukemia in children. The clinical presentation is similar to that of AML. The lymphocytic nature of blasts is confirmed by demonstrating lymphocytic markers, such as terminal deoxynucleotide transferase (TdT).
Chronic myelogenous leukemia (CML; choice C) is also a disorder of middle-aged persons. Neoplastic bone marrow precursors in this condition are still capable of differentiating along myeloid lines, so that most circulating leukemic cells appear as mature white blood cells. CML is a myeloproliferative disorder, so the platelet count and erythrocyte count are usually normal or even increased. Leukocytosis in CML is usually striking, often higher than 500,000/mm3. The Philadelphia chromosome, the result of a balanced translocation between 9q and 22q, is present in 95% of cases.
A leukemoid reaction (choice D) is defined as an abnormal elevation of the white cell count in response to infections. Circulating leukocytes, however, are normal in morphology and never exceed 50,000/mm3. Leukocyte alkaline phosphatase is useful in differentiating leukemoid reaction from myeloid leukemia. The enzyme is elevated in leukemoid reaction but low in leukemia.
Myelodysplastic syndromes (choice E) constitute a complex set of bone marrow disorders, in which at least two cell lines are affected. These conditions are characterized by cytopenias (anemia, thrombocytopenia, and/or neutropenia) associated with hypercellular bone marrow. Cytopenias are due to ineffective hematopoiesis. The progression is usually indolent, but transformation to acute leukemia occurs in some cases.
A previously healthy 30-year-old man is injured in an automobile accident. He is taken to the emergency department, where he is noted to have multiple lacerations of his extremities, some of which are bleeding profusely. His blood pressure is 70/palpable mm Hg. The decision is made to transfuse 2 units of blood after rapid cross- matching. No reactions are detected in the blood bank. Ten minutes after the transfusion, the patient develops a severe case of hives. The development of hives in this setting would be most likely to be seen in a patient with which of the following syndromes?
(A) Adenosine deaminase deficiency (B) Ataxia telangiectasia
(C) DiGeorge syndrome
(D) Selective IgA deficiency
(E) Wiskott-Aldrich syndrome
Respuesta: D
The correct answer is D. Selective IgA deficiency is a relatively common condition (1 in 700 incidence in Caucasians), in which patients are genetically unable to synthesize IgA for either serum or bodily secretions. The underlying defect is a failure of B cells to differentiate into IgA-producing plasma cells. Most individuals with selective IgA deficiency are asymptomatic; about 5% have recurrent respiratory tract infections. The condition becomes clinically significant when blood transfusion is required, since they may develop anaphylaxis when exposed to blood products containing IgA. This can happen even on the first transfusion, presumably because they have been exposed to IgA in animal products that they have eaten. The condition can be confirmed with serum electrophoresis studies, which show an absence of IgA. Once diagnosed, the individuals (and families) need to be taught to tell their physicians about the IgA deficiency, so that only IgA free transfusions will be used.
Adenosine deaminase deficiency (choice A) is a cause of severe combined immunodeficiency.
Ataxia telangiectasia (choice B) is characterized by cerebellar ataxia, telangiectasias, and immunodeficiency.
DiGeorge syndrome (choice C) is characterized by hypoparathyroidism, thymic aplasia, and deficient T cell function.
Wiskott-Aldrich syndrome (choice E) is characterized by thrombocytopenia, lymphopenia, and atopic eczema.
A 48-year-old man comes to the physician because of a 2-day history of severe low back pain. He states that he has had periodic low back pain for years, but this is more severe than usual and radiates to the buttock and down the right leg. His temperature is 36.8 C (98.2 F). Examination shows some rigidity of the lumbar spine. The pain is exacerbated by applying pressure on the paravertebral region in the lower lumbar spine and by passively raising the leg at 45 degrees while the patient lies supine. A reduced Achilles tendon reflex is noted. Which of the following is the most appropriate next step in management?
(A) MRI examination of vertebral column
(B) Nonsteroidal anti-inflammatory drugs (NSAIDs) and 2 days of bed rest
(C) Plain x-ray examination of the lumbosacral spine
(D) Radionuclide bone scanning
(E) Surgical consultation
Respuesta: B
The correct answer is B. The clinical picture strongly suggests herniation of an intervertebral disc causing compression of a spinal root (S1, considering radiation of the pain and reflex alterations). Supporting such a diagnosis is also the positive straight leg-raising test (Lasegue sign). When the history and physical examination support a diagnosis of disc herniation, conservative management is all that is needed. Current recommendations include treatment with NSAIDs and bed rest of short duration (no longer than 2 days). Longer periods of bed rest do not provide any additional benefit.
MRI examination of vertebral column (choice A) is certainly the diagnostic procedure of choice to visualize soft tissue structures of the vertebral column. MRI is reserved for cases in which more detailed imaging information would change the therapeutic approach.
Plain x-ray examination of the lumbosacral spine (choice C) provides nonspecific information. Almost any person older than 40 has some signs of degenerative joint disease of the lumbar column. Plain radiographs should be performed when the clinical symptomatology suggests diseases other than disc herniation, such as tumors or infections.
Radionuclide bone scanning (choice D) is useful in detecting foci of osteomyelitis or bone metastases, but not disc disease.
Surgical consultation (choice E) should be sought if the patient does not respond to appropriate treatment or if there are severe or evolving neurologic deficits. Percutaneous lumbar discectomy may be performed under local anesthesia as an alternative to laminectomy.
A 71-year-old man presents with a complaint of dyspnea for the past week. The patient has a history of diabetes and hypertension and was recently diagnosed with cancer. He is currently on multiple drug therapy. On examination, temperature is 37.2 C (99.0 F), his blood pressure is 140/90 mm Hg, pulse is 90/min, and respirations are 22/min. His lungs have a few crackles at the bases with no wheezing. A chest x-ray film shows bilateral diffuse interstitial markings. Which of the following medications is likely responsible for the patient’s dyspnea?
(A) Bleomycin
(B) Cisplatin
(C) Mithramycin
(D) Verapamil
(E) Vincristine
Respuesta: A
The correct answer is A. Bleomycin can cause pneumonitis, which progresses to pulmonary fibrosis. Cough and shortness of breath are indications of the development of this complication. The pulmonary toxicity is usually age-and dose-related, although an allergic form of pneumonitis has been reported.
Cisplatin (choice B) produces tinnitus, hearing loss, and nephrotoxicity.
Mithramycin (choice C) is associated with hemolytic uremic syndrome, thrombocytopenia, hepatotoxicity, and nephrotoxicity.
Calcium-channel blockers, such as verapamil (choice D), cause headache, dizziness, and nausea. They may increase the extent of heart block and worsen congestive heart failure.
Vincristine (choice E) causes neuropathy rather than pulmonary symptoms.
A 30-year-old woman complains of fatigue and dyspnea for the past 2 months. She reports that she has also lost 15 pounds during this time. She has been previously healthy and is not taking any medications. She is pale and thin and has a flow murmur on her cardiac examination. She also has mildly enlarged supraclavicular lymph nodes. Laboratory results are notable for a hematocrit of 30%, mean corpuscular volume (MCV) of 78 μm3, decreased transferrin iron binding capacity (TIBC), and increased ferritin. A screening erythrocyte protoporphyrin level is <35 μg/dL, and a blood smear shows microcytic red cells. Which of the following is the most likely diagnosis?
(A) Anemia of chronic disease
(B) Aplastic anemia
(C) Lead poisoning
(D) Pyridoxine deficiency
(E) Spherocytosis
(F) Thiamine deficiency
Respuesta: A
The correct answer is A. This is anemia of chronic disease. In contrast to iron deficiency anemia, the TIBC is decreased, but ferritin is increased. The microcytosis is the same as in iron deficiency. This patient may have an infection or an occult malignancy and needs further workup for the loss of weight.
Aplastic anemia (choice B) can be the result of exposure to drugs, such as chloramphenicol, that can lead to the suppression of erythrocyte production. A low reticulocyte count, which is an indication of immature red cells, can be helpful in diagnosis of this illness. Bone marrow biopsy may show hypocellularity of the marrow.
Lead poisoning (choice C) occurs following the inhalation of lead dust or fumes or following the ingestion of lead. Presentation in these patients ranges from abdominal discomfort, myalgia, headache, and weight loss to peripheral neuropathy and encephalopathy. Laboratory studies show a normal serum iron, a normal TIBC, and basophilic stippling on peripheral blood smear. A screening erythrocyte protoporphyrin level is >35 μg/dL, indicating the need for blood lead testing.
Pyridoxine is a cofactor in the manufacture of porphyrins, which are needed in the manufacture of hemoglobin. Therefore, pyridoxine deficiency (choice D) may cause a microcytic hypochromic anemia, but the laboratory panel above is characteristic of anemia of chronic disease.
Hereditary spherocytosis (choice E) is a genetic defect arising from mutations in red cell cytoskeletal proteins. This leads to a cell wall defect, which in turn leads to removal of excess cell wall in the spleen. Surface tension causes these cells to become spheres.
Thiamine deficiency (choice F) has been implicated in a rare megaloblastic anemia in children. It is also seen in malnourished alcoholics, and intramuscular repletion is often required.
A 50-year-old man comes to the physician because of an unusual appearing mole on his upper back. He says that his wife has noted a recent change in its color and shape. The lesion measures 0.7 cm and has ill-defined margins and irregular pigmentation. The patient is otherwise healthy and takes no medication. Which of the following is the most appropriate next step in management?
(A) Follow-up examination in 6 months
(B) Topical application of Podophyllum resin
(C) Cryotherapy with liquid nitrogen
(D) Shave biopsy
(E) Incisional biopsy
(F) Excisional biopsy
Respuesta: F
The correct answer is F. The gross appearance of the lesion, along with its recent changes over a presumably short period, is highly suggestive of malignant melanoma. The proportion in which melanomas arise from pre-existing benign nevocellular nevi is not known. In the dysplastic nevus syndrome, however, a dysplastic nevus-melanoma sequence is well established. Nevertheless, an excisional biopsy should be carried out in any case of pigmented skin lesion that shows one or more of the following features: asymmetric or fuzzy border, irregular or variegated color, and diameter greater than 0.6 cm. According to the American Cancer Society, the mnemonic ABCD may serve to recall the most important suspicious signs: Asymmetry, Border irregularity, Color variegation, and Diameter >0.6 cm. Bleeding and ulcerations are malignant signs, albeit far less frequent. Melanoma is the most common cause of death due to skin malignancies. Physicians can play a crucial role in prevention by referring to dermatologists patients who have moles with such suspicious features. The initial approach to a suspicious mole or clinically obvious melanoma consists of total excision (excisional biopsy) with a small margin. If a diagnosis of melanoma is confirmed pathologically, wider margins are excised on a second operation.
Follow-up examination in 6 months (choice A) would result in a dangerous delay in diagnosis and treatment.
Topical application of Podophyllum resin (choice B) and cryotherapy with liquid nitrogen (choice C) are treatments used for common and genital warts, as well as for other common benign lesions, such as seborrheic keratosis. These methods should never be used on pigmented lesions.
Shave biopsy (choice D) is applicable to many types of superficial skin lesions, including basal cell carcinomas, but is inappropriate for melanomas. Proper diagnosis and evaluation of depth of invasion in melanomas can be achieved only on full-thickness biopsies.
Incisional biopsy (i.e., partial sampling; choice E) is not appropriate unless the lesion is too extensive (such as giant congenital nevi or lentigo maligna). However, there seems to be no foundation for the belief that incisional biopsy facilitates cancer spread.
A 52-year-old man with a history of chronic low back pain complains of 3 days of a cough productive of purulent sputum, fever, and left-sided subcostal pain worsened by breathing. A single episode of shaking chills accompanied the onset of the illness. He has no gastrointestinal complaints. His temperature is 40 C (104 F), blood pressure is 160/80 mm Hg, pulse is 100/min, and respirations are 38/min with nasal flaring and splinting. The cardiac and abdominal examinations are within normal limits. There are moist crackles and egophony at the left lung base. A chest x-ray film shows a left lower lobe infiltrate. Gram stain of the sputum shows multiple polymorphonuclear leukocytes and occasional epithelial cells. Which of the following is the most likely pathogen?
(A) Gram-negative diplococci
(B) Gram-negative rods
(C) Gram-positive cocci in clusters
(D) Gram-positive diplococci in chains
(E) Gram-positive rods
Respuestas: D
The correct answer is D. This patient is demonstrating the classic picture of pneumococcal pneumonia. Streptococcus pneumoniae is the most common cause of community-acquired pneumonia in this age group. The usual presentation is sudden onset of shaking chills, with rigors, high fever, and difficulty breathing. Pleuritic chest pain is often present and signifies bacterial infection. A white blood cell count, not provided in this case, most often is significantly elevated with a left shift (predominantly bands and polymorphonuclear cells). Chest x-ray films usually reveal a lobar distribution of the pneumonia. Pleural effusions are present in up to 30% of the cases. Gram stain of the sputum commonly reveals gram-positive diplococci in chains.
Gram-negative diplococci (choice A) would be present in pneumonia due to Moraxella catarrhalis (formerly Branhamella catarrhalis). This pathogen may produce acute pneumonia and usually occurs in the elderly or in those with a history of chronic bronchitis or obstructive lung disease.
Gram-negative rods (choice B) are not a usual cause of pneumonia in this population of patients. Gram-negative rods causing pneumonia include Klebsiella, Enterobacter, Serratia, and Proteus, which occur more commonly in patients who are debilitated or residing in nursing homes or similar institutions. These bacteria are often responsible for nosocomial pneumonias and, infrequently, community-acquired pneumonia.
Gram-positive cocci in clusters (choice C) that cause pneumonia are usually Staphylococcus aureus. S. aureus is an uncommon cause of community-acquired pneumonia. When it does cause disease, it is usually during or just following an epidemic of viral influenza. S. aureus may be seen year-round in the hospital, because it is a common cause of nosocomial pneumonia.
Gram-positive rods (choice E) would likely be Corynebacterium diphtheriae (diphtheria). This patient presents with pneumonia, not diphtheria (an infection that occurs in the pharynx, middle ear, larynx, skin, or bronchi).
A 38-year-old man who works as a reporter for a travel magazine comes to his physician because of the acute onset of jaundice, malaise, and temperatures to 38.5 C (101 F). He had returned from Burma 2 weeks ago, where he spent 4 weeks. He says that he abstains from alcohol beverages and does not take any medications. Laboratory studies show elevated serum aminotransferases, high bilirubin (both total and direct), and negative serology for hepatitis A virus (HAV) and C virus (HCV) infection. He was vaccinated for hepatitis B virus (HBV) 3 years ago and is now positive for anti- HBsAg antibodies. Which of the following serologic markers should be tested as the most appropriate next step in diagnosis?
(A) Anti-HCV IgG antibodies by RIBA
(B) Anti-HDV IgG antibodies
(C) Anti-HEV IgM antibodies
(D) Anti-HGV IgG antibodies
(E) HBsAg
Respuesta: C
The correct answer is C. Hepatitis E virus (HEV) is rare in the U.S., but outbreaks of acute hepatitis E occur in some countries, namely Mexico, India, Afghanistan, and Burma. The infectious agent is transmitted by the oralfecal route, usually from infected water. HEV hepatitis is generally self-limited, but it is important to note that it carries a 10% to 20% mortality rate in pregnant women. Similar to HAV, HEV infection does not cause chronic hepatitis or a carrier state. The onset of IgM antibodies to HEV is concomitant with the appearance of clinical symptomatology, whereas IgG will become detectable after the acute phase.
RIBA (recombinant immunoblot assay) for anti-HCV antibodies (choice A) is used to confirm a diagnosis of hepatitis C in patients with positive anti-HCV antibodies by the more conventional enzyme immunoassay test. The latter has a 50% specificity, and false positive results are likely in patients with hypergammaglobulinemia. Occasionally, HCV RIBA is also used when the enzyme immunoassay is negative, but there are strong clinical grounds to suspect that the patient has HCV hepatitis. There is no reason to suspect HCV hepatitis in this case.
Anti-HDV antibodies (choice B) are found in association with hepatitis D virus infection. HDV is a “defective” RNA virus that causes hepatitis only in the presence of the surface antigen of HBV (HBsAg). In the U.S., HDV is usually associated with IV drug abuse. HDV may coinfect or superinfect patients with HBV. Superinfection is associated with increased risk for fulminant hepatitis or rapid progression to cirrhosis.
Anti-HGV antibodies (choice D) are found in 50% of IV drug abusers and 30% of patients receiving hemodialysis. HGV is a flavivirus transmitted by the parenteral route. The infection is followed by viremia lasting for at least 10 years. The pathogenic role of HGV is still uncertain.
HBsAg (choice E) detection implies ongoing HBV replication in the organism. HBsAg appears first in the blood before HBV infection becomes clinically evident. Persistence of HBsAg is associated with infectivity. HBV infection would be most unlikely in this case, since the patient developed anti-HBV antibodies after vaccination.
A 50-year-old man returns to his home in Minnesota after a diving trip to Belize (Central America). The day after his return, he comes to the physician because of diarrhea, abdominal cramps, and nausea. His temperature is 37 C (98.6 F). His stools do not contain mucus or blood. Microscopic examination of a stool sample reveals no leukocytes. Which of the following is the most likely pathogen?
(A) Bacillus cereus
(B) Clostridium perfringens
(C) Escherichia coli
(D) Rotavirus
(E) Staphylococcus aureus
Respuesta: C
The correct answer is C. Traveling abroad often entails abrupt changes in diet and climate, as well as exposure to conditions of poor sanitation, all of which results in a high incidence of diarrhea. This is self-limiting and manifests with watery diarrhea and dehydration, but no fever or other signs of systemic infection. The most frequent cause of traveler’s diarrhea is enterotoxigenic Escherichia coli.
The remaining infectious agents listed here are all potential causes of noninflammatory diarrhea, which is not associated with blood and mucus in the stool, fever, systemic signs of infection, or fecal leukocytes.
Bacillus cereus (choice A), Clostridium perfringens (choice B), and Staphylococcus aureus (choice E), along with enterotoxigenic E. coli, are the most common agents associated with food poisoning due to production of toxins. All these pathogens produce a similar clinical picture of watery diarrhea, sometimes with nausea and vomiting, but no fever.
Rotavirus (choice D) is one of the most important infectious causes of diarrhea in infants and young children in developing countries. It may also cause diarrhea in adults exposed to infected children.
A 65-year-old man with a history of peripheral vascular disease develops thromboembolic disease in his left leg accompanied by dry gangrene. Laboratory tests show elevated serum lactic acid, and his arterial pH is 7.27. An ECG in this patient is most likely to show which of the following?
(A) Peaked T waves
(B) QT prolongation
(C) ST depression
(D) T wave inversion
(E) U waves
Respuesta A
The correct answer is A. Peaked T waves are associated with significant hyperkalemia that may lead to arrhythmia. In this patient, the primary mechanism of hyperkalemia is acidosis. As a result of the lowered pH, the extracellular concentration of protons increases, thereby increasing the H+/K+ antiports on the cell surface, driving protons into the cells and potassium into the extracellular space. ECG changes are an indication for immediate correction of the hyperkalemia, indicating an increased risk of arrhythmia. Calcium gluconate should be administered to decrease membrane excitability.
Hypocalcemia causes prolonged QT intervals (choice B). The QT interval is the time difference between ventricular depolarization and repolarization. Since the QT interval depends on the heart rate, the corrected QT interval (QTc) is often used. The correction factor incorporates the interval between consecutive P waves.
ST depression (choice C) would be seen in an ischemic event. It is important to compare the new ECG with an old one to determine whether the depression is new. If this is the case, the patient with such ECG changes should at least be placed on aspirin and observed for an ischemic event.
T wave inversion (choice D) is another indication that the patient may be undergoing an ischemic event. Once again, it is important to compare the new ECG with an old one. Furthermore, if the new ECG shows upright T waves, but the old one shows inverted T waves, this denotes “pseudonormalization” and once again indicates an ischemic event.
U waves (choice E) are seen in hypokalemia. If an ECG shows these changes, the risk of an arrhythmia is significant, and the hypokalemia must be corrected immediately. This can usually be achieved by administering oral potassium, but occasionally IV potassium may be required.
A 35-year-old man has had nocturnal attacks of severe periorbital headache for the past 5 days. Each episode awakens him at night within 2 hours of falling asleep, lasts for less than an hour, and is associated with ipsilateral rhinorrhea and lacrimation. There is no family history of similar headaches. Careful evaluation does not reveal any objective evidence of neurologic dysfunction. The pupils are equal and normally reactive to light. His temperature is 37 C (98.6 F), blood pressure is 125/75 mm Hg, and pulse is 72/min. Which of the following is the most likely diagnosis?
(A) Cluster headache
(B) Depression headache
(C) Giant cell arteritis
(D) Migraine
(E) Tension headache
(F) Trigeminal neuralgia
Respuesta: A
The correct answer is A. The clinical presentation is characteristic of cluster headache. In its classic form, cluster headache manifests as nocturnal attacks that last between 30 minutes and 2 hours. These are often precipitated by alcohol consumption and recur daily for up to 8 weeks. Each “cluster” is then followed by a pain-free interval lasting for 1 year on average. The pathogenesis is probably related to disturbances of the serotoninergic pathways originating from the raphe nuclei. Acute attacks may be shortened by oxygen, sumatriptan, and ergotamine preparations; several prophylactic agents are available to prevent clusters.
Depression headache (choice B) is often worse in the morning and is frequently associated with other manifestations of depression.
The headache due to giant cell arteritis (choice C) usually manifests in elderly patients and is associated with scalp tenderness over the affected superficial temporal artery. Systemic signs and symptoms are present, including myalgia, weight loss, and malaise. The erythrocyte sedimentation rate is elevated.
Classic cases of migraine (choice D) begin in early adulthood and manifest as episodic unilateral throbbing headache, often associated with nausea, photophobia, and visual symptoms.
Tension headache (choice E) has a diffuse, band-like character and feels worse in the back of the head. Pain slowly increases and may last for many hours or even days.
Trigeminal neuralgia (choice F) is a disorder of the sensory nucleus of CN V that produces episodic, severe, and lancinating pain in the distribution of one or more divisions of the trigeminal nerve. Pain is often precipitated by well defined trigger zones (e.g., washing or shaving) and is not associated with Horner syndrome or rhinorrhea.
A 32-year-old African American woman complains of mild fevers and fatigue for the past month. She has no significant past medical history. Her temperature is 38.1 C (100.6 F), blood pressure is 115/70 mm Hg, pulse is 75/min, and respirations are 18/min. Nontender, mobile, cervical and axillary lymph nodes are noted. Auscultation of the lungs reveals fine crackles bilaterally. A chest x- ray film shows hilar lymphadenopathy and diffuse interstitial infiltrates. Lymph node biopsy shows noncaseating granulomas. Which of the following is the most appropriate therapy?
(A) Allopurinol
(B) Angiotensin converting enzyme (ACE) inhibitor
(C) Cyclosporine
(D) Glucocorticoids
(E) Isoniazid
Respuesta: D
The correct answer is D. This patient has pulmonary sarcoidosis. The peak age group for sarcoidosis is 20-40 years, and the disease seems to be more common in blacks. Noncaseating granulomas can occur in the lungs, heart, kidneys, skin, liver, or other organs. Most characteristically, the patients are asymptomatic, and the disease is detected by an abnormal chest x-ray film, which usually shows bilateral symmetric hilar adenopathy often associated with paratracheal adenopathy and/or parenchymal infiltrates. Patients may have uveitis, peripheral arthritis, skin involvement with granulomas, or erythema nodosum. The lungs are the most frequently involved organ; pulmonary symptoms, when present, include dyspnea on exertion, nonproductive cough, and wheezing. Radiologic abnormalities are graded 0-3. Grade 0 is associated with a normal x-ray. Grade 1 is associated with lymph node enlargement without pulmonary parenchymal abnormalities. Grade 2A is a combination of lymph node and diffuse pulmonary parenchymal disease. Grade 2B is a diffuse parenchymal disease without lymph node enlargement. Grade 3 is associated with radiographic changes indicating more chronic disease with pulmonary fibrosis (“honey- combing”). Many patients show spontaneous total remission of disease for a period up to 3 years. Prednisone is usually the drug of choice for treatment, with a starting dose of 30-40 mg/day.
Neither allopurinol (choice A) nor cyclosporine (choice C), an immune modulator, has been proven to be of benefit in sarcoidosis.
Levels of ACE may be elevated in patients with sarcoidosis but are also elevated in many other diseases. This enzyme elevation is thought to be related to induction by the granulomas. There is no evidence that ACE inhibitors (choice B) have any therapeutic value in treatment of sarcoidosis. At one point in history, some theorized that sarcoidosis was caused by a type of mycobacterium, related to tuberculosis. However, this has not been definitively proven. Furthermore, isoniazid (choice E) has not been shown to be beneficial.
A 20-year-old man comes to the physician because he has noticed blood in his urine on several occasions in the past year. Each episode of hematuria occurred in association with an upper respiratory tract infection or a flulike illness. Physical examination is unremarkable. A urine dipstick test shows mild proteinuria and microhematuria. Serum levels of electrolytes, creatinine, and blood urea nitrogen are within normal limits. Serum levels of IgA are elevated. Which of the following is the most likely diagnosis?
(A) Berger disease
(B) Goodpasture syndrome
(C) Henoch-Schönlein purpura
(D) Minimal change disease
(E) Postinfectious glomerulonephritis
(F) Wegener granulomatosis
Respuesta: A
The correct answer is A. The clinical presentation is consistent with Berger disease or IgA nephropathy, the most frequent form of glomerulonephritis in the U.S. (and probably worldwide). Often, microhematuria or mild proteinuria occurs as an incidental finding or as recurring episodes following upper respiratory or intestinal infections. IgA deposition in the mesangium is the most characteristic morphologic abnormality, and serum IgA is increased in 50% of patients (hence the designation). Up to 50% of patients will eventually progress to chronic renal failure.
Goodpasture syndrome (choice B) typically involves both the lungs and kidneys. Hemoptysis and nephritic syndrome are the clinical manifestations. Linear deposition of anti-collagen antibodies along the glomerular and pulmonary basement membranes is the pathognomonic finding on biopsy. This is a severe condition that requires aggressive immunosuppressive treatment.
The renal changes of Henoch-Schönlein purpura (choice C) are very similar to those of Berger disease. These conditions, in fact, are thought to represent different manifestations of a common spectrum of diseases, in which autoimmune damage is mediated by IgA. In Henoch-Schönlein purpura, nephritic syndrome is associated with palpable purpura, arthralgias, and abdominal pain. The disorder usually affects children.
Minimal change disease (choice D) is characterized by edema, albuminuria, and changes in blood lipids and proteins. It is usually seen in children, and it doesn’t present with episodic hematuria. Proteinuria is of the nephrotic range.
Postinfectious glomerulonephritis (choice E) commonly occurs 1-2 weeks after an infection by group A Streptococcus (pharyngitis or impetigo) and manifests with nephritic syndrome. Hematuria developing in the setting of Berger disease, instead, is concomitant with an upper respiratory infection (so-called sympharyngitic hematuria).
Wegener granulomatosis (choice F) is a necrotizing granulomatous vasculitis involving the upper respiratory system and the kidneys. Systemic symptoms are present, with fever, weight loss, and malaise. Aggressive immunosuppression is the mainstay of therapy.
A 60-year-old woman presents to a physician complaining of a swelling in her neck. Her past medical history is significant for rheumatoid arthritis and Sjögren syndrome. Physical examination reveals a mildly nodular, firm, rubbery goiter. Total serum thyroxine (T4) is 10 mg/dL, and third-generation thyroid-stimulating hormone (TSH) testing shows a level of 1.2 mIU/mL. Antithyroid peroxidase antibody titers are high. Which of the following is the most likely diagnosis?
(A) Euthyroid sick syndrome
(B) Graves disease
(C) Hashimoto thyroiditis
(D) Silent lymphocytic thyroiditis
(E) Subacute thyroiditis
Respuesta: C
The correct answer is C. Hashimoto disease is a chronic, destructive lymphocytic infiltration of the thyroid glands. It is probably the most common cause of primary hypothyroidism in the U.S. It has an 8:1 female predominance and increases in incidence with age. Many patients also have other autoimmune diseases. The description of the goiter in the question stem is typical of that produced by Hashimoto disease; the physical signs and symptoms of hypothyroidism are also present in longer-standing cases. Early in the disease, as in this case, T4 and TSH levels may be normal. Antithyroid peroxidase antibodies (against the specific antigen formerly detected with antimicrosomal antibodies) are observed in almost all patients with Hashimoto disease, but can also sometimes be detected in patients with Graves disease and silent lymphocytic thyroiditis.
Euthyroid sick syndrome (choice A) occurs in patients with severe systemic illness who are clinically euthyroid but have abnormal thyroid function tests.
Graves disease (choice B) causes diffuse toxic goiter and would exhibit both the signs and laboratory findings of hyperthyroidism.
Silent lymphocytic thyroiditis (choice D) usually occurs in postpartum women and may be a mild, usually spontaneously reversible, variant of Hashimoto disease.
Subacute thyroiditis (choice E) is a virally caused acute inflammatory disease that causes thyroid tenderness and pain.
A 22-year-old man comes to the physician because he has developed patches of hair loss in his scalp and beard over several months. The patient’s medical history is unremarkable, but his family history is significant for Addison disease in a sister and vitiligo in his mother. Physical examination shows two sharply demarcated areas of total hair loss in the scalp and one in the right cheek. The skin in these areas is perfectly smooth and covered only by sparse short hair shafts. In addition, pitting of nail plates is noted. A biopsy of affected skin demonstrates lymphocytic infiltrates around hair follicles. Which of the following is the most appropriate next step in management?
(A) Psychiatric consultation
(B) Topical application of minoxidil
(C) Oral administration of iron sulfate
(D) Topical injections of corticosteroids
(E) Systemic corticosteroids
Respuesta: E
The correct answer is D. The skin condition described is alopecia areata, a form of baldness that may affect any region of the body. Its pathogenesis is probably immunerelated, considering the frequent association with autoimmune disorders, such as Hashimoto thyroiditis, pernicious anemia, and Addison disease. The finding of perifollicular lymphocytic infiltration in affected areas seems to support an autoimmune origin. The patches of hair loss in alopecia areata are rather haphazardly distributed but sharply demarcated. An important feature is the presence of “exclamation hairs” (tiny hair shafts) in the zone of active shedding. In 80% of cases, the hair regrows spontaneously, but permanent loss is observed in the other 20%. Local injection of triamcinolone or application of anthralin ointment has been beneficial in hastening recovery.
Psychiatric consultation (choice A) may be appropriate for trichotillomania, a compulsive habit of pulling one’s own hair. In this disorder, the patches of hair loss are often unilateral (on the right side if the patient is right-handed, and vice versa), have irregular borders, and consistently show growing hairs.
Topical application of minoxidil (choice B) is widely used for treatment of the most common form of alopecia, namely androgenetic baldness, which is related to androgenic hormonal influences. The pattern of androgenetic baldness is characteristic and well known. Minoxidil treatment results in temporary hair regrowth, especially in patients younger than 50 and those with less extensive areas of hair loss.
Oral administration of iron sulfate (choice C) may be beneficial in another form of alopecia, named telogen effluvium. In this condition, an increased number of hairs are lost daily on combing or shampooing. It is due to an increase in the percentage of hairs in telogen (resting) phase and occurs in association with severe malnutrition, termination of pregnancy, stress from surgery or infection, and oral contraceptives. However, some studies have indicated that iron deficiency may play an important causative role in telogen effluvium.
Systemic corticosteroids (choice E) have not been shown to have any advantage over local injection in cases of alopecia areata.
A 75-year-old white man complains to a physician of abdominal pain. His temperature is 37 C (98.6 F), blood pressure is 110/65 mm Hg, pulse is 63/min, and respirations are 16/min. The abdomen is soft, with focal tenderness in the left lower quadrant. His erythrocyte count is 4.5 million/mm3, leukocyte count is 9000/mm3 with 60% neutrophils and 5% bands, and platelet count is 250,000/mm3. Serum chemistries show:
Sodium Potassium Chloride Creatinine Urea nitrogen
140 mEq/L 5 mEq/L 102 mEq/L 1.1 mg/dL 12 mg/dL
Which of the following is the most appropriate next step in diagnosis?
(A) Barium enema
(B) Colonoscopy
(C) CT of abdomen
(D) Plain film of abdomen
(E) Trial therapy of a liquid diet
Respuesta: E
The correct answer is E. The probable diagnosis is diverticulitis. The relatively mild symptoms, normal vital signs, and normal laboratory values in this patient indicate that he is not very ill. This means that he can be treated at home with rest, a liquid diet, and oral antibiotics, such as cephalexin. In this setting, the response to the therapeutic trial itself serves as a confirmatory test. In most cases, the symptoms will resolve rapidly on this regimen, and the diet can be gradually advanced to a soft, low-roughage diet supplemented with daily psyllium seed extract. At approximately 1 month, a high- roughage diet is resumed. Seriously ill patients with diverticulitis are usually treated in the hospital and may require IV antibiotics. Surgery will be needed in only about 20% of these patients.
Barium enema studies (choice A), typically with air contrast, can be performed if necessary at 2 weeks to confirm the presence of diverticula.
Colonoscopy (choice B) can be used alternatively to barium enema at 2 weeks to identify diverticula and rule out other conditions, such as proctitis or colon cancer, which would not be as likely in this patient with mild symptoms.
CT of the abdomen (choice C) is used in severe cases when the differential diagnosis includes pelvic abscess and appendicitis.
Plain film of the abdomen (choice D) is of limited utility in this setting but may show increased gas in the bowel if the diverticulitis has lowered intestinal motility.
A 38-year-old man comes to the physician because of slowly progressive visual problems that make him “bump into objects” on both sides. He also reports that, while driving, he has trouble switching lanes because he needs to turn his head all the way backward to look for other cars. Ocular examination shows bitemporal field loss with preserved visual acuity. Examination of the fundus is unremarkable. Which of the following is the most likely diagnosis?
(A) Pituitary adenoma
(B) Occipital lobe meningioma
(C) Optic glioma
(D) Optic nerve atrophy
(E) Optic neuritis
(F) Retinal detachment
Respuesta: A
The correct answer is A. The visual deficit present in this patient is described as bilateral temporal hemianopia and is due to chiasmatic lesions that compromise the crossing fibers originating from the temporal retina. A large pituitary adenoma (macroadenoma) that extends beyond the sella turcica into the suprasellar region is the most common cause of temporal hemianopia. Craniopharyngioma and meningioma are other causes.
Occipital lobe meningioma (choice B) may push on the visual cortex and produce visual symptoms that are referred to the contralateral half of the visual field (homonymous hemianopia).
Optic glioma (choice C) is a tumor of glial origin, usually an astrocytoma, that develops within the optic nerve. Visual symptoms develop slowly and are referred to the ipsilateral eye.
Optic nerve atrophy (choice D) involves damage to the nerve from ischemia, inflammation, glaucoma, toxic substances, and trauma. Symptoms include diminished visual acuity, reduced visual fields, abnormal color vision, and poor pupillary response to light. The optic disc appears pale or white on ophthalmoscopy.
Optic neuritis (choice E) will result in unilateral visual loss that develops rapidly. Multiple sclerosis is an important cause of optic neuritis.
Retinal detachment (choice F) results in blurring of vision that affects only one eye. Myopia and cataract extraction are the two most common predisposing factors.
An 18-year-old woman complains of myalgias, a sore throat, and painful mouth sores for 3 days’ duration. Her temperature is 38.2 C (100.8 F), blood pressure is 110/80 mm Hg, pulse is 84/min, respirations are 15/min. Her gingiva are edematous and erythematous, and there are vesicles on her right upper and lower lips. Her pharynx is mildly erythematous but without exudate, and there is tender mobile cervical lymphadenopathy. Her breath is not fetid, and the dentition is normal. Which of the following is the most likely causal agent?
(A) Actinomyces israelii
(B) Coxsackie virus
(C) Herpes simplex virus 1
(D) Nocardia asteroides
(E) Streptococcus pyogenes
Respuesta: C
The correct answer is C. Gingivostomatitis and pharyngitis are the most frequent clinical manifestations of primary herpes simplex virus 1 (HSV-1) infection, and are most commonly seen in children and young adults. Clinical signs and symptoms include fever, malaise, myalgias, and cervical adenopathy. Common lesions may involve the hard and soft palate, gingiva, tongue, lips, and facial area. The lesions are classically vesicular with an erythematous base.
Actinomyces israelii (choice A) causes an indolent suppurative infection. These anaerobic actinomycetes are commensals of the gastrointestinal tract and mouth. The organism may invade via a break in the oral mucosa or via aspiration into the lung. Poor dental hygiene and dental abscesses predispose to cervicofacial lesions. Infection presents as a chronic suppurative lesion with adjacent tissue showing inflammation with fibrosis and draining sinuses. Myalgias and low-grade fevers are rare with facial actinomycetes.
Coxsackie virus (choice B) infection may result in herpangina, an exanthematous disease characterized by acute onset of fever and sore throat. Small vesicular lesions and white papules (lymph nodules) surrounded by a red halo are typically seen over the posterior half of the palate, pharynx, and tonsillar areas. Lip and facial lesions are rare.
Nocardia asteroides (choice D) are aerobic actinomycetes that cause disease most often in the lung, but also at any site of tissue trauma. Lesions produced by Nocardia show suppuration, necrosis, and abscess formation with sinus tracts draining purulent material.
Streptococcus pyogenes (choice E) causes streptococcal pharyngitis, with the highest incidence in children aged 5-15 years. Patients usually present with the sudden onset of sore throat, particularly with pain on swallowing. Associated symptoms include fever, malaise, headache, and anorexia. On examination, there is diffuse edema and erythema of the posterior pharynx. The tonsils, if present, are enlarged and erythematous with an exudate. The cervical nodes are tender and enlarged. Oral lesions are limited to the posterior pharynx.
A 35-year-old man complains to a physician of chronic vague gastric pain of several years’ duration. The pain is sometimes relieved by food. Serum immunoglobulin studies for IgG and IgA antibodies directed against Helicobacter pylori are strongly positive. Endoscopy with gastric antral biopsy demonstrates gastritis but no ulcerative lesions. H. pylori organisms are seen with special stains on the biopsy fragments. The patient is treated with a 1-week course of omeprazole (20 mg bid), plus clarithromycin and metronidazole (500 mg bid each). Which of the following is the most appropriate test to noninvasively determine whether the H. pylori has been eradicated?
(A) Culture of gastric biopsy
(B) Rapid urease test
(C) Repeat qualitative IgA and IgG antibodies against H. pylori
(D) Repeat quantitative IgA and IgG antibodies against H. pylori
(E) Urea breath test
Respuesta: E
The correct answer is E. Helicobacter pylori is a small, gram- negative bacterium that lives in and locally destroys the mucus coating that lines the stomach. The organism has been linked to a wide variety of problems, including gastritis, peptic ulcer disease, gastric cancer, and gastric lymphoma. Because of these associations, physicians are tending to become more aggressive about therapy. H. pylori is a hardy organism and requires concurrent therapy with multiple agents for eradication. The original regimen combined bismuth subsalicylate (Pepto-Bismol), tetracycline, and metronidazole, and had only an 80% cure rate in compliant patients who followed the regimen for 2 weeks. The schedule listed in the question stem is a more modern one; it is both easier to follow and has a better cure rate. Alternative regimens may substitute amoxicillin (1 g bid) for metronidazole, or may substitute lansoprazole (30 mg bid) for omeprazole. These more effective regimens have caused a problem in determining whether eradication has occurred, however, because the course is so short that IgG and IgA antibodies against H. pylori have not had time to decrease by the end of therapy. The urea breath test is a relatively new test in which the patient is given oral urea that has been labeled with 13C or 14C. The H. pylori bacteria contain the enzyme urease and are able to metabolize the urea, producing radioactively labeled CO2, which can be measured in breath samples taken 20-30 minutes after ingestion. It is recommended that this test be delayed until 4 weeks after the end of the regimen, since recent antibiotic use may have decreased the number of organisms enough to produce a negative test, without having achieved true eradication.
Culture of gastric biopsy (choice A) is highly specific but requires both endoscopic biopsy and fastidious culture technique. Therefore, this method is not often used clinically for follow-up studies.
The rapid urease test (choice B) is performed on gastric tissue. It is rapid, specific, and sensitive, but requires endoscopy to obtain the biopsy fragment.
Qualitative assays of antibodies against H. pylori (choice C) may be positive for up to 3 years after eradication of the infection.
Quantitative assays of antibodies against H. pylori (choice D) drop slowly for up to a 3 years after eradication of the infection
A 52-year-old man comes to the physician because of slowly progressive weakness in his legs. He also complains of clumsiness with his right hand, which creates difficulties with buttons or turning keys. Examination reveals mild bilateral footdrop and leg weakness. Fasciculation and mild wasting are observed in the calf muscles. There is no spasticity or impaired sensation. The speech is normal, but fasciculation of the tongue is appreciated. Respiration, pulse, and temperature are normal. A muscle biopsy shows evidence of denervation with reinnervation. Which of the following is the most likely diagnosis?
(A) Amyotrophic lateral sclerosis (ALS)
(B) Charcot-Marie-Tooth disease
(C) Guillain-Barré syndrome
(D) Myasthenia gravis
(E) Spinal muscular atrophy
Respuesta: A
The correct answer is A. Flaccid paresis involving the lower extremities, footdrop, hand clumsiness, muscle wasting, and especially fasciculation in a middle-aged person are highly suggestive of amyotrophic lateral sclerosis (ALS). This results from degeneration of the motor neurons in the spinal cord (lower motor neuron) and leads to denervation of skeletal muscle. His tongue fasciculations result from degeneration of motor neurons of cranial nerve nuclei (XII). Continued bulbar involvement will likely eventually affect pharyngeal and facial musculature, leading to progressive dysarthia and dysphasia. Surviving neurons may reinnervate denervated myofibers by sprouting of their axons. The finding of denervation/reinnervation in a muscle biopsy is confirmatory of the clinical diagnosis. The patient will later develop evidence of corticospinal and corticobulbar (upper motor neuron) degeneration as his disease progresses.
Charcot-Marie-Tooth disease (choice B) is an autosomal recessive demyelinating disease of peripheral nerve that manifests in children or young adults with marked atrophy of the calf muscles and distal muscle weakness. For this reason, the disorder is also known as peroneal muscular atrophy.
Guillain-Barré syndrome (choice C) manifests with ascending paralysis (first the lower, then the upper extremities are involved) and results from a chronic inflammatory response leading to demyelination of peripheral nerves. It is often preceded by an upper respiratory tract infection.
Myasthenia gravis (choice D) is characterized by fluctuating muscle weakness that usually begins in the ocular muscles, resulting in diplopia and ptosis. Since the disorder is due to impaired cholinergic transmission at the neuromuscular junction, skeletal muscle biopsy is within normal limits at the light microscopic level.
Spinal muscular atrophy (SMA; choice E) is the infantile counterpart of ALS. SMA is a group of hereditary disorders, the most frequent form of which is Werdnig-Hoffmann disease (SMA type 1), which leads to death by the third year of life.
An 18-year-old man is referred for evaluation of hypertension. On examination, he appears in no apparent discomfort and states that he has never had any health problems. His height is 175 cm (69 in), and his weight is 70 kg (154 lb). There is no pitting edema in the lower legs or jugular vein distention. The lungs are clear to auscultation. Blood pressure is 162/80 mm Hg in the upper extremities and 115/77 mm Hg in the lower extremities. Femoral pulses are weaker than radial pulses. A systolic murmur is appreciated at the base of the heart and is particularly intense in the back. The ECG shows changes consistent with left ventricular hypertrophy, and a chest x- ray film reveals notching of the inferior margins of the ribs. Which of the following is the most likely diagnosis?
(A) Atrial septal defect (ASD)
(B) Coarctation of the aorta
(C) Congenital aortic stenosis
(D) Congenital pulmonary stenosis
(E) Patent ductus arteriosus
(F) Tetralogy of Fallot
(G) Ventricular septal defect (VSD)
Respuesta B
The correct answer is B. The specific signs that suggest the correct diagnosis include the wide discrepancy between the blood pressure in the upper extremities and lower extremities, the systolic murmur heard on the back, and the notching of the ribs appreciated on x-ray. Coarctation of the aorta, in its most frequent (adult) type, consists of a stenotic aortic segment just distal to the origin of the left subclavian artery. Hypertension develops in the branches proximal to the stenosis, and hypotension in the aorta distal to it. In the most severe forms, the patients may develop left ventricular failure in infancy, but the most common presenting picture is that of a young adult with hypertension, which may lead to left ventricular hypertrophy or cerebral hemorrhage.
Atrial septal defect (ASD) (choice A) is generally asymptomatic. A large ASD usually leads to right ventricular failure in middle age. A systolic murmur is heard at the pulmonary area, and S2 is widely split.
Congenital aortic stenosis (choice C) gives rise to a harsh systolic murmur heard along the left sternal border and radiating to the neck. It is due to congenitally abnormal, usually bicuspid, aortic valves.
Congenital pulmonary stenosis (choice D) is a rare form of congenital valvular disease. Mild-to-moderate stenosis is usually asymptomatic, but severe cases result in right-sided heart failure or sudden death. A systolic murmur is heard at the second left intercostal space, often preceded by an ejection click.
Adults with a small or medium-size patent ductus arteriosus (choice E) are usually asymptomatic until middle age. This anomaly is associated with a characteristic continuous “machinery-like” murmur, which is maximal at the pulmonary area and often accompanied by a thrill.
Tetralogy of Fallot (choice F) is the most common form of cyanotic congenital heart disease. The four features include subpulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy. The degree of subpulmonary stenosis is the single most important determinant of the clinical severity and symptomatology. Most infants present with early cyanosis.
Ventricular septal defect (VSD) (choice G) is the most frequent congenital cardiac anomaly. Most cases are asymptomatic. Large VSDs lead to right ventricular overload and are associated with a harsh pansystolic murmur along the left sternal border associated with a thrill.
A 50-year-old alcoholic man with chronic hepatitis C infection is brought to the emergency department by the police, who notice that the man has blisters and crusted lesions on sun-exposed skin of his face and lower arms. Plasma porphyrins are elevated, and follow-up studies demonstrate elevated uroporphyrin I in urine and isocoproporphyrin in feces. A biopsy of one of the lesions reveals subepidermal blisters with minimal inflammation, thickening of vessel walls in the papillary dermis, marked solar elastosis, and “caterpillar bodies” in the roof of the blister. Which of the following is the most likely diagnosis?
(A) Acute intermittent porphyria
(B) Delta-aminolevulinic acid dehydratase deficiency
(C) Erythropoietic protoporphyria
(D) Hereditary coproporphyria
(E) Porphyria cutanea tarda
Respuesta: E
The correct answer is E. Porphyria cutanea tarda is the most common of all of the porphyrias, and is consequently a likely target on the USMLE. It causes chronic blistering and crusting lesions on sun-exposed skin. The defective enzyme in heme synthesis is uroporphyrinogen decarboxylase. Precipitating factors include iron (even in normal amounts in some cases), estrogen use, alcohol use, and chronic hepatitis C infection. Skin biopsy can be helpful but is usually not completely specific (the “caterpillar bodies” in the question stem are clumps of basement membrane material). Porphyrin analyses demonstrate the findings in the question stem.
Acute intermittent porphyria (choice A) is one of the more common forms of porphyria and typically presents with severe abdominal pain.
Delta-aminolevulinic acid dehydratase deficiency (choice B) is a rare form of porphyria that can cause abdominal pain and hemolysis.
Erythropoietic porphyria (choice C) is one of the more common forms of porphyria and typically presents with acute, rather than chronic, photosensitivity with pain and swelling after sunlight exposure.
Hereditary coproporphyria (choice D) is a rare porphyria than presents with abdominal pain.
A 40-year-old woman is admitted to the hospital because of fever, headache, confusion, and jaundice for 1 week. She underwent hysterectomy 2 months ago and began estrogen replacement therapy with ethinyl estradiol and a progestin. On admission, her temperature is 38.7 C (102 F), blood pressure is 140/90 mm Hg, pulse is 98/min, and respirations are 20/min. She appears disoriented to time and place. Physical examination reveals jaundiced sclerae and skin, purpura on the trunk, and bleeding gums. A guaiac stool test is positive for occult blood. Blood and urine cultures are
negative, show:
Hematocrit - 28%
Red blood cells - 2.5 million/mm3
Leukocytes - 10,000/mm3
Platelets - 15,000/mm3
Serum BUN - 40 mg/dL
Serum Creatinine - 2.8 mg/dL
Serum LDH - 800 U/L
Total Bilirubin - 4.0 mg/dL
Direct Bilirrubin - 0.8 mg/dL
Coagulation tests are within normal limits; fibrin-split products and Coombs test are negative. A peripheral blood smear shows schistocytes, helmet cells, and triangle cells. Which of the following is the most likely diagnosis?
(A) Disseminated intravascular coagulation (DIC)
(B) Evans syndrome
(C) Hemolytic-uremic syndrome (HUS)
(D) Idiopathic (autoimmune) thrombocytopenic purpura (ITP)
(E) Malignant hypertension
(F) Thrombotic thrombocytopenic purpura (TTP)
Respuesta F:
The correct answer is F. The key data to make a correct diagnosis include the following: severe thrombocytopenia, which results in a bleeding diathesis; elevated indirect bilirubin and high LDH with schistocytes in the blood smear, indicating microangiopathic hemolytic anemia; renal dysfunction (high creatinine); and neurologic and systemic symptoms (headache, confusion, and fever). Negative findings important to rule out similar conditions include a negative Coombs test and absence of fibrin split products. Thrombotic thrombocytopenic purpura (TTP) is a disorder of unclear pathogenesis, perhaps related to circulating platelet-agglutinating factors. It presents with a characteristic combination of microangiopathic hemolytic anemia, fever without infection, neurologic symptoms, bleeding diathesis secondary to thrombocytopenia, and renal impairment. This condition may be precipitated by pregnancy or use of estrogens.
Disseminated intravascular coagulation (DIC; choice A) can be differentiated from TTP because of abnormal coagulation tests. In DIC, microangiopathic hemolysis is also present, but prothrombin time (PT) is prolonged, fibrinogen levels are reduced, and fibrin split products are elevated.
Evans syndrome (choice B) refers to coexistence of autoimmune hemolytic anemia (positive Coombs test), and autoimmune thrombocytopenic purpura (see choice D).
Hemolytic-uremic syndrome (HUS; choice C) is not significantly different from TTP. The two conditions, in fact, are considered manifestations of the same pathogenetic spectrum. However, the vascular bed of the CNS is not involved in HUS; thus, mental status changes are not part of the clinical picture.
Idiopathic (autoimmune) thrombocytopenicpurpura (ITP; choice D) is an immune disorder caused by autoantibodies to platelet antigens. Systemic illness is not present in ITP, which is characterized by isolated thrombocytopenia without other hematologic abnormalities. Ten percent of cases will manifest in association with autoimmune hemolytic anemia (Evans syndrome).
Malignant hypertension (choice E) may cause microangiopathic hemolytic anemia. However, blood pressure values would be extremely elevated.
