2-1 through 2-2. The answers are 2-1 a, 2-2 d. (Behrman, 16/e, pp 1285-1287. McMillan, 3/e, pp 1214-1216. Rudolph, 20/e, pp 672-677.) Of the choices given, bronchiolitis is the most likely, although asthma, pertussis, and bronchopneumonia can present similarly. The family history of upper respiratory infections, the previous upper respiratory illness in the patient, and the signs of intrathoracic airway obstruction make the diagnosis of bronchiolitis more likely. Viral croup, epiglottitis, and diphtheria are not reasonable choices because there are no signs of extrathoracic airway obstruction.

The most likely cause of the illness is infection by respiratory syncytial virus, which causes outbreaks of bronchiolitis of varying severity, usually in the winter and spring. Other viruses, such as parainfluenza and the adenoviruses, have also been implicated in producing bronchiolitis. Treatment is usually supportive in this generally self-limited condition. Ribavirin, an expensive antiviral agent, is reserved for the most severe cases, those who have congenital heart disease, BPD, immune deficiency, and chest wall abnormalities.

2-3. The answer is b. (Schwartz, 7/e, pp 1158-1161.) Corrosive injuries of the esophagus most frequently occur in young children due to accidental ingestion of strong alkaline cleaning agents. Significant esophageal injury occurs in 15% of patients with no oropharyngeal injury, while 70% of patients with oropharyngeal injury have no esophageal damage. Signs of airway injury or imminent obstruction warrant close observation and possibly tracheostomy. The risk of adding injury, particularly in a child, makes esophagoscopy contraindicated in the opinion of most surgeons. Administration of oral "antidotes" is ineffective unless given within moments of ingestion; even then, the additional damage potentially caused by the chemical reactions of neutralization often makes use of them unwise. A barium esophagogram is usually done within 24 h unless evidence of perforation is present. In most reports, steroids in conjunction with antibiotics reduce the incidence of formation of strictures from about 70% to about 15%. Vomiting should be avoided, if possible, to prevent further corrosive injury and possible aspiration. It is probably wise to avoid all oral intake until the full extent of injury is ascertained.

2-4. The answer is d. (Chin, 17/e, pp 75-77, 521-525.) Clinical symptoms caused by Mycobacterium bovis are indistinguishable from those of M. tuberculosis. This patient is unlikely to have been in contact with someone with active tuberculosis (TB), given that he lives in a rural area. His occupation, however, may lead to contact to M. bovis. Brucellosis may also cause fever, sweats, fatigue, but is not associated with cough. The incubation period generally does not exceed 2 mo.

2-5. The answer is d. (Barnett, 3/e, pp 945-948. Osborn, pp 192-194.) Cerebral amyloid angiopathy (CAA), or congophilic angiopathy, is the most common cause of lobar hemorrhage in elderly patients without hypertension. The deposition of amyloid beta protein, the same as that found in Alzheimer's disease, in brain blood vessels leads to disruption of the vessel walls that predisposes these patients to hemorrhage. Patients are usually over age 70, and may present with multiple cortical hemorrhages with or without a history of dementia. At times, additional hemorrhages may be seen only with the use of special imaging techniques such as gradient echo magnetic resonance imaging (MRI), which magnifies the effects of hemosiderin in regions of prior hemorrhage.

2-6. The answer is a. (Yudofsky, 3/e, pp 455-459.) The patient's perse-cutory delusions and disorganized thinking could suggest a psychotic disorder such as schizophrenia or brief reactive psychosis, but fluctuations in consciousness and disorientation are typically found in delirium. Disturbances in memory, language, and sleep-wake cycles are also typical of delirium. Delusions, hallucinations, illusions, and misperceptions are also common. The causes of delirium are many and include metabolic encephalopathies, such as the hyperglycemic encephalopathy experienced by the patient in the vignette; intoxication with drugs and poisons; withdrawal syndromes; head trauma; epilepsy; neoplasms; vascular disorders; allergic reactions; and injuries caused by physical agents (heat, cold, radiations).

2-7. The answer is c. (Schwartz, 7/e, pp 966-967.) Acute mesenteric ischemia may be difficult to diagnose. The condition should be suspected in patients with either systemic manifestations of arteriosclerotic vascular disease or low cardiac output states associated with a sudden development of abdominal pain that is out of proportion to the physical findings. Lactic aci-dosis and an elevated hematocrit reflecting hemoconcentration are common laboratory findings. Abdominal films show a nonspecific ileus pattern. The cause may be embolic occlusion or thrombosis of the superior mesenteric artery, primary mesenteric venous occlusion, or nonocclusive mesenteric ischemia secondary to low cardiac output states. A mortality of 65% to 100% is reported. The majority of affected patients are at high operative risk, but since early diagnosis followed by revascularization or resectional surgery or both is the only hope for survival, celiotomy must be performed once the diagnosis of arterial occlusion or bowel infarction has been made. Initial treatment of nonocclusive mesenteric ischemia includes measures to increase cardiac output and blood pressure and the direct intraarterial infusion of vasodilators such as papaverine into the superior mesenteric system. The patient presented in the question is at risk for both occlusive and nonocclusive mesenteric ischemic disease. If his clinical status permits, angiographic studies should be performed before the operation to establish the diagnosis and to determine whether embolectomy, revascularization, or nonsurgical management is indicated as initial treatment.

2-8 through 2-9. The answers are 2-8 b, 2-9 a. (Fauci, 14/e, pp 1026-1027.) The diffuse rash involving palms and soles would in itself suggest the possibility of secondary syphilis. The hypertrophic, wartlike lesions around the anal area are called condyloma lata and are specific for secondary syphilis. The Venereal Disease Research Laboratory (VDRL) slide test will be positive in all patients with secondary syphilis. The WeilFelix titer has been used as a screening test for rickettsial infection. In this patient who has condyloma and no systemic symptoms, Rocky Mountain spotted fever would be unlikely. No chlamydial infection would present in this way. Blood cultures might be drawn to rule out bacterial infection such as chronic meningococcemia; however, the clinical picture is not consistent with a systemic bacterial infection. Penicillin is the drug of choice for secondary syphilis. Ceftriaxone and tetracycline are usually considered to be alternate therapies. Interferon a has been used in the treatment of condyloma acuminata, a lesion that can be mistaken for syphilitic condyloma.

2-10. The answer is a. (Behrman, 16/e, pp 519-521. McMillan, 3/e, pp 359-362. Rudolph, 20/e, pp 1168-1170, 1176-1180, 1203-1207.) The absence of a major blood group incompatibility and the finding of a normal reticulocyte count argue strongly in favor of a recent fetomaternal transfusion, probably at the time of delivery. A Betke-Kleihauer stain for fetal hemoglobin-containing red cells in the mother's blood would confirm the diagnosis. After birth, erythropoiesis ceases, and the progressive decline in hemoglobin values, reaching a nadir at 6 to 8 wk of age, has been termed physiologic anemia of infancy. Iron-deficiency anemia is common in the term infant between 9 and 24 mo of age, when the iron stores derived from circulating hemoglobin have been exhausted and an exogenous dietary source of iron has not been provided. The manifestations of sickle cell disease do not appear until 4 to 6 mo of life, coincident with the replacement of fetal hemoglobin with sickle hemoglobin.

2-11. The answer is d. (Sadock, 7/e, p 1691.) This patient suffers from restless legs syndrome, a disorder characterized by the irresistible urge to move one's legs while trying to fall asleep. Patients describe the unpleasant feelings in their calves as worms or ants crawling. Only moving the legs or walking alleviates the discomfort. Restless legs syndrome can be caused by pregnancy, anemia, renal failure, and other metabolic disorders.

2-12. The answer is c. (Stein, 5/e, p 2290.) A film of the right hip is mandatory in this patient. Fracture of the hip must be ruled out, particularly in a woman with mental status abnormalities who may be prone to falls.

2-13. The answer is b. (Wallace, 14/e, pp 1247-1249.) Elders who are disabled are more likely to suffer from physical abuse or neglect. Most abuse occurs at the hands of a relative, and most abused elders are likely to live with the abuser, who is often stressed both emotionally and financially as the elder requires more care. Many abused elders become depressed as a result of abuse.

2-14. The answer is d. (Behrman, 16/e, p 1782. McMillan, 3/e, p 1797. Rudolph, 20/e, p 1817.) Glucose is nonenzymatically attached to hemoglo bin to form glycosylated hemoglobin. The major component of this reaction proceeds very slowly and is irreversible until the hemoglobin is destroyed. The concentration of glycosylated hemoglobin thus reflects glucose concentration over the half-life of the red cell, or about 2 to 3 mo.

2-15. The answer is b. (Adams, 6/e, pp 180-182.) The term cluster headache refers to the tendency of these headaches to cluster in time. They may be distinctly seasonal, but the triggering event is unknown. The pain of cluster headache is usually described as originating in the eye and spreading over the temporal area as the headache evolves. In contrast to migraine, men are more often affected than women, and extreme irritability may accompany the headache. The pain usually abates in less than an hour. Affected persons routinely have autonomic phenomena associated with the headache that include unilateral nasal congestion, tearing from one eye, conjunctival injection, and pupillary constriction. The autonomic phenomena are on the same side of the face as the pain. These phenomena are similar to those elicited by the local action of histamine and gave rise to the now largely abandoned term of Horton histamine headaches.

2-16. The answer is a. (Lewis, 2/e, pp 579-580. Sadock, 7/e, p 2741.) Although the relationships between emotional deprivation and failure to thrive are complex, the fact that children who are emotionally deprived do not grow well even when an adequate amount of food is available is well proved. Renee Spitz studied institutionalized children and demonstrated that, due to lack of adequate nurturing, they become apathetic, withdrawn, and less interested in feeding, which in turn causes failure to thrive and, in extreme cases, death. Spitz called this syndrome "analytic depression." Schizophrenia and autism have not been associated with emotional deprivation in infancy.

2-17. The answer is d. (Stobo, 23/e, pp 138-139.) This patient's chronic cough, hyperinflated lung fields, abnormal pulmonary function tests, and smoking history are all consistent with chronic bronchitis. A smoking cessation program can decrease the rate of lung deterioration and is successful in as many as 40% of patients, particularly when the physician gives a strong antismoking message and uses both counseling and nicotine replacement. Continuous low-flow oxygen becomes beneficial when arterial oxygen concentration falls below 55 mm Hg. Antibiotics are only indi cated for acute exacerbations of chronic lung disease, which might present with fever, change in color of sputum, and increasing shortness of breath. Oral corticosteroids are helpful in some patients, but are reserved for those who have failed inhaled bronchodilator treatments.

2-18. The answer is c. (Hales, 3/e, pp 570-573.) This patient displays typical symptoms of recurrent panic attacks. Panic attacks can occur in a wide variety of psychiatric and medical conditions. The patient is diagnosed with panic disorder when there are recurrent episodes of panic and there is at least 1 mo of persistent concern, worry, or behavioral change associated with the attacks. The attacks are not due to the direct effect of medical illness, medication, or substance abuse and are not better accounted for by another psychiatric disorder. While anxiety can be intense in generalized anxiety disorder, major depression, acute psychosis, and hypochondriasis, it does not have the typical acute presentation described here.

2-19. The answer is c. (Bradley, 3/e, p 1446.) This patient has a gradually progressive myelopathy. The differential diagnosis is broad, but multiple sclerosis (MS) is high on the list. A subset of patients with MS consists of middle-aged men with a progressive form of the disease. MRI of the spinal cord could show MS plaques in the cord or other abnormalities intrinsic to the spinal cord parenchyma, and could also exclude compressive lesions. Vascular malformations of the spinal cord can also be seen in this way, although sometimes spinal angiography is required for definitive diagnosis. Cerebral angiography would not be helpful except to evaluate for residual aneurysm, which is unlikely to be related to this patient's problem. Spinal cord biopsy is unwarranted in this case unless a specific indication is provided on neuroimaging. Visual evoked responses may be abnormal in MS, even without clinical evidence of disease, but would not account for this patient's spastic paraparesis.

2-20. The answer is e. (Schatzberg, 2/e, pp 259-260.) Bupropion is an effective antidepressant, and it has been found to be as effective as stimulants in treating attention deficit hyperactive disorder (ADHD) in children and adults. It may exacerbate tics in children with comorbid Tourette disorder.

2-21. The answer is b. (Tintinalli, 5/e, pp 229-250.) The early phase of septic shock is characterized by vasodilation, resulting in a warm, flushed patient with a normal or elevated cardiac output. Fever, agitation, or confusion is often present. In late septic shock, patients become obtunded with decreased cardiac output and hypotension that is not reversible by volume replacement. Patients with cardiogenic shock have signs of pulmonary vascular congestion (jugular venous distension, S3 gallop, bilateral lung crackles), increased pulmonary capillary wedge pressure (PCWP), and decreased cardiac output. Neurogenic shock follows a spinal cord injury (warm skin, bradycardia, neurologic deficits), and hypovolemic shock is characterized by a physical examination consistent with volume depletion (tachycardia; hypotension; cool, clammy skin; poor capillary refill) and decreased PCWP. A mnemonic to remember the causes of shock is SHOCK: Sepsis, Hypovolemia, Other (i.e., Addison's disease), CNS (neurogenic), and Kardiac causes.

2-22. The answer is d. (Greenberg, 2/e, ch 2, p 18.) According to the table, 10 new cases of tuberculosis developed among the 500 persons belonging to households with a case of tuberculosis at the time of the first survey. Because these 500 persons were followed for 2 years, the number of person-years of exposure is 1000. Therefore, the incidence rate is calculated as follows:

10 new cases

= 10 cases per 1000 person-years

500 persons X 2 years

2-23. The answer is c. (Greenberg, 2/e, ch 2, p 18.) Ten new cases of tuberculosis developed among 10,000 persons belonging to households that had no culture-positive cases at the time of the first survey. Since these 10,000 persons were followed for 2 years, the number of person-years of exposure is 20,000. Therefore, the incidence rate is calculated as follows:

10 new cases

= 0.5 cases per 1000 person-years

10,000 persons X 2 years

2-24. The answer is e. (Greenberg, 2/e, ch 2, pp 98-99.) The relative risk is the ratio of the incidence of a disease in a group exposed to a factor (in this case, household contact with tuberculosis) to the incidence in a group not exposed to the factor (persons without household contact). Therefore, the relative risk is

Incidence in households with exposure 10

incidence in households without exposure 0.5

Identification of groups with a high level of relative risk can be useful in planning disease control programs.

2-25. The answer is a. (Yudofsky, 3/e, pp 842-843.) Multiple cerebral infarcts cause a progressive dementia, focal neurological signs and, often, neuropsychiatric symptoms, such as depression, mood lability (but not usually elated mood), and delusions. Loose associations, catatonic posturing, and bizarre proverb interpretations are typical symptoms of schizophrenia.

2-26. The answer is e. (Sabiston, 15/e, pp 324-325. Schwartz, 7/e, pp 199-200.) Penetrating injury to the intraperitoneal or extraperitoneal rectum should be diagnosed by immediate sigmoidoscopy. Contrast studies of the rectum, when sigmoidoscopy is inconclusive, should use a water-soluble radiopaque medium such as Gastrografin. The use of barium is contraindicated since spillage of barium mixed with feces into the peritoneal cavity would increase the likelihood of subsequent intraabdominal abscesses. Instrumentation of the bullet track is also contraindicated because of the risk of injury to adjacent structures (e.g., bladder, ureters, iliac vessels). Angiography is not a sensitive method for demonstrating injury to the intestinal wall.

2-27. The answer is d. (Rock, 8/e, pp 121-122.) The clinical history presented in this question is a classic one for a ruptured tubal pregnancy accompanied by hemoperitoneum. Because pregnancy tests are negative in almost 50% of cases, they are of little practical value in an emergency. Dilation and curettage would not permit rapid enough diagnosis, and the results obtained by this procedure are variable. Posterior colpotomy requires an operating room, surgical anesthesia, and an experienced operator with a scrubbed and gowned associate. Refined optic and electronic systems have improved the accuracy of laparoscopy, but this new equipment is not always available, and the procedure requires an operating room and, usually, surgi cal anesthesia. Culdocentesis is a rapid, nonsurgical method of confirming the presence of unclotted intraabdominal blood from a ruptured tubal pregnancy. Culdocentesis, however, is also not perfect, and a negative culdocen-tesis should not be used as the sole criteria for whether or not to operate on a patient.

2-28. The answer is d. (Tintinalli, 5/e, pp 1278-1280.) The definition of drowning is death from suffocation after submersion. Fresh water drowning in swimming pools is actually more common than saltwater drowning. The patient described has noncardiogenic pulmonary edema, which is a complication of near-drowning (survival after suffocation from submersion). This is a result of direct pulmonary injury, loss of surfactant, and contaminants in the water. Respiratory failure, severe hypothermia, and neurologic injury are the three most common threats to life after submersion.

2-29. The answer is a. (Stobo, 23/e, pp 794-796.) The first step in evaluating a scrotal mass is to determine whether or not the mass is in the testis or outside the testis. Most solid masses arising from within the testis are malignant. Palpation of the scrotal mass and transillumination (holding a flashlight directly against the posterior wall of the scrotum) will distinguish testicular lesions from other masses within the scrotum, such as hydrocele. Ultrasonography will confirm a solid testicular mass. Human chorionic gonadotropin (hCG) and a fetaprotein are important in assessment of seminoma versus nonseminomatous testicular cancer once testicular mass lesion is confirmed.

2-30. The answer is b. (Mishell, 3/e, pp 179-182.) Vaginismus is painful spasm of the pelvic muscles and vaginal outlet. It is usually psychogenic. It should be differentiated from frigidity, which implies lack of sexual desire. Treatment is primarily psychotherapeutic, as organic vulvar (such as atrophy, Bartholin's gland cyst, or abscess) or pelvic causes are very rare. Vaginismus should be differentiated from dyspareunia, which is deep pelvic pain with coitus. Dyspareunia is frequently associated with pelvic pathology such as endometriosis, pelvic adhesions, or ovarian neoplasms.

2-31. The answer is b. (Seidel, 4/e, p 481.) An acquired arteriovenous fistula may be diagnosed by the presence of a continuous murmur and a pal pable thrill over an area of previous trauma. The large pulse pressure is an indication that a large portion of the cardiac output is bypassing the systemic vascular resistance through the fistula.

2-32. The answer is c. (Schwartz, 7/e, pp 601-602, 1717.) The thyroid gland originates embryologically from the foramen cecum at the base of the tongue. Normally, the thyroglossal duct becomes obliterated and resorbed, but portions may remain patent and become filled with serous fluid, which produces a midline cervical mass. Observe that in the scan of the patient described in the question, the mass is central and appears not to be part of the gland itself.

2-33. The answer is d. (Berson, pp 40-49.) A cataract is opacity of the lens; patients often present complaining of a disturbance in vision. When the lens has a cataract, the red reflex is diminished and it becomes difficult to see the fundus through the opacity. Patients with macular degeneration present with central vision loss, and drusen bodies (yellow-white lesions), retinal atrophy, and neovascularization are often found on funduscopic examination. Presbyopia is a decreased ability to focus on near objects (because of loss of accommodation) that occurs with aging. Glaucoma is an insidious disease, and symptoms occur late in the disease. Patients complain of peripheral vision loss (central vision is spared until late in the disease) and scotomas. Intraocular pressure is usually elevated.

2-34. The answer is c. (Greenfield, 2/e, pp 1109-1127.) Various types of colonic polyps can be distinguished on pathologic examination. Adeno-matous polyps are distributed throughout the entire large bowel, more commonly in the right and left colon than the rectum. They are often pedunculated and show an increased number of glands compared with normal mucosa. Although polyps that appear in familial polyposis are indistinguishable from single adenomatous polyps, they manifest much earlier in life. Carcinomatous changes in patients who have familial poly-posis occur approximately 20 years before carcinomatous changes of the bowel occur among patients in the general population.

2-35. The answer is c. (Pozgar, 7/e, pp 476-477.) The major issues are confidentiality and duty to warn a third party. When a person initially learns that he or she is human immunodeficiency virus (HIV) positive, this information in itself is often overwhelming. The patient may not feel able or willing to inform exposed partners. The best approach is to try to convince the patient of the necessity of this, perhaps at a later visit. Some states have enacted laws that allow the physician to inform third parties of HIV exposure, but only after efforts by the physician have failed to convince the person to disclose. These laws protect the physician against legal liability for breach of confidentiality, but they do not obligate the physician to disclose to third parties. Some few state laws allow only state disease intervention specialists (DISs) to inform third parties of HIV exposure after the physician has contacted DIS. Many states do not have any of these laws, and the only option is to try to convince an infected patient to disclose. As a rule, for all other sexually transmitted diseases (STDs), partner notification is confidential and voluntary, and the DISs cannot inform third parties without the consent of the infected person, even if requested by the physician. They can assist consenting infected persons in informing contacts either by doing it for them (contacts are never informed of the source) or coaching them to do it themselves.

2-36. The answer is b. (Stobo, 23/e, pp 324-330.) The primary treatment for Type 2 diabetes is dietary. About half of all patients can maintain normal blood sugar with weight reduction. If weight reduction fails, a number of oral hypoglycemics are available as the next step.

2-37. The answer is b. (Behrman, 16/e, pp 1126-1127. McMillan, 3/e, pp 618-619. Rudolph, 20/e, pp 1062-1063.) Endoscopic examination of the esophagus and stomach is a diagnostic method of determining the extent of the mucosal injury. Vomiting is to be avoided since it would expose the mucosal surfaces to the caustic agent a second time. The child can be given small amounts of milk or water, but large amounts, which might cause vomiting, are unwise. Neutralization of the caustic can result in an exothermic reaction and produce a thermal burn. The use of steroids after endoscopy in second-degree chemical burns of the esophagus has been effective in diminishing the inflammatory response in some patients. Optimal treatment is still controversial and requires expert consultation or review of the most current literature. Charcoal, however, does not absorb the alkaline agent in drain cleaner.

2-38. The answer is b. (Schwartz, 7/e, pp 1253-1255.) The effects of radiation on the intestine depend on a variety of factors, which include the age of the patient, temperature, degree of oxygenation, and metabolic activity. Acute intestinal radiation injury is manifested in the bowel by the cessation of viable cell production and is seen clinically as diarrhea or gastrointestinal bleeding. Progressive vasculitis and fibrosis are seen in the latter stages.

2-39. The answer is d. (Adams, 6/e, p 1208.) The rapid onset of bulbar paresis is consistent with acute inflammatory demyelinating polyneuropa-thy (AIDP, or Guillain-Barre syndrome), botulism, tick paralysis, and several other conditions. The normal conduction velocities argue against demyelinating neuropathy, which may be associated with Campylobacter jejuni. Cytomegalovirus (CMV), and Treponema pallidum may cause several different neurologic syndromes, but acute bulbar paresis is not among them. Chlamydia pneumoniae is under investigation as a cause of atherosclerosis, strokes, and multiple sclerosis, but does not cause acute motor weakness.

2-40. The answer is c. (Adams, 6/e, p 1208.) Botulism is a disorder of the neuromuscular junction (NMJ). The characteristic findings are decremen-tal response of the muscles to repetitive stimulation of the nerve at a low frequency (2 to 5 Hz) and incremental response to repetitive stimulation at high frequency (20 to 50 Hz). Other disorders of the NMJ, such as myas-thenia gravis and Lambert-Eaton myasthenic syndrome (LEMS), also manifest with decremental response to repetitive stimulation at low frequencies due to depletion of acetylcholine in the synaptic cleft. Higher rates of stimulation lead to increased calcium in the presynaptic terminal, which allows more acetylcholine to be released in presynaptic disorders such as botulism and LEMS, thereby increasing the response of muscle. In myasthenia gravis, which is characterized by loss of acetylcholine receptors postsynap-tically, there is no increase in response at higher rates of stimulation, since there is already a maximal amount of acetylcholine present in the synaptic cleft. Abnormal visual evoked and brainstem auditory evoked potentials are seen in disorders affecting central pathways, as in multiple sclerosis. Conduction block occurs in demyelinating disorders affecting the nerves. Fibrillation potentials are present in denervation and certain myopathic conditions; they may occur in botulism, as well as in patients treated with botulinum toxin for therapeutic purposes, but this is not diagnostic of clinical botulism.

2-41. The answer is c. (Behrman, 16/e, pp 35-37. McMillan, 3/e, pp 756-761. Rudolph, 20/e, pp 121-128.) At 6 to 61/2 mo of age, infants are able to sit alone, leaning forward to support themselves with arms extended— the so-called tripod position. They can reach for an object by changing the orientation of the torso. They can purposefully roll from a prone to supine as well as from a supine to prone position. By 12 mo, they can grasp a pellet between the thumb and forefinger without ulnar support. Motor development occurs in a cephalocaudal and central-to-peripheral direction. Therefore, truncal control precedes arm control, which precedes finger dexterity.

2-42. The answer is c. (LaDou, 2/e, p 398.) Carbon disulfide, chloro-prene, estrogens, excessive heat, lead, and ionizing radiation have all been strongly linked to oligospermia. Exposure to lead can occur during the manufacturing of storage batteries. Chromium, nickel, and antimony levels are measured in urine and are not associated with oligospermia.

2-43. The answer is c. (Fauci, 14/e, pp 1941-1944.) Tophaceous gout is characterized by the finding in synovial fluid of monosodium urate crystals that are needle-shaped and strongly negative birefringent (bright yellow when parallel to the axis). Gouty attacks may be precipitated by trauma, medications that inhibit tubular secretion of uric acid (aspirin, hydro-chlorothiazide), surgery, stress, alcohol, and a high-protein diet. Patients may have an accumulation of tophi in and around the joints and earlobes. Radiographs may show "rat bite" erosions. Pseudogout is due to deposition of calcium pyrophosphate dihydrate (CPPD); these crystals are rhomboid-shaped and weakly positive birefringent (blue when parallel to the axis). Calcium oxalate deposition disease is usually seen in patients with endstage renal disease, and calcium phosphate deposition disease causes cal-cific tendinitis or Milwaukee shoulder.

2-44. The answer is c. (Reece, 2/e, pp 1142-1145.) The most probable diagnosis in this case is acute pancreatitis. The pain caused by a myoma in degeneration is more localized to the uterine wall. Low-grade fever and mild leukocytosis may appear with a degenerating myoma, but liver function tests are usually normal. The other "obstetric" cause of epigastric pain, severe preeclamptic toxemia (PET), may exhibit disturbed liver function

[sometimes associated with the HELLP syndrome (hemolysis, elevated liver enzymes, low platelets)], but this patient has only mild elevation of blood pressure and no proteinuria. Acute appendicitis in pregnancy is one of the more common nonobstetric causes of abdominal pain. In pregnancy, symptoms of acute appendicitis are similar to those of nonpregnant patients, but the pain is more vague and poorly localized and the point of maximal tenderness moves with advancing gestation to the right upper quadrant. Liver function tests are normal with acute appendicitis. Acute cholecystitis may cause fever, leukocytosis, and pain of the right upper quadrant with abnormal liver function tests, but amylase levels would be only mildly elevated, if at all, and the pain would be less severe than described in this patient. The diagnosis that fits the clinical description and the laboratory findings is acute pancreatitis. This disorder may be more common during pregnancy, with an incidence of 1:100 to 1:10,000 pregnancies. Cholelithiasis, chronic alcoholism, infection, abdominal trauma, some medications, and pregnancy-induced hypertension are known predisposing factors. Patients with pancreatitis are usually in acute distress— the classic finding is a person who is rocking with knees drawn up and trunk flexed in agony. Fever, tachypnea, hypotension, ascites, and pleural effusion may be observed. Hypotonic bowel sounds, epigastric tenderness, and signs of peritonitis may be demonstrated on examination.

Leukocytosis, hemoconcentration, and abnormal liver function tests are common laboratory findings in acute pancreatitis. The most important laboratory finding is, however, an elevation of serum amylase levels, which appears 12 to 24 h after onset of clinical disease. Values may exceed 200 U/dL (normal values are 50 to 160 U/dL). A useful diagnostic tool in the pregnant patient with only modest elevation of amylase values is the amylase/creatinine ratio. In patients with acute pancreatitis, the ratio of amylase clearance to creatinine clearance is always greater than 5% to 6%.

Treatment considerations for the pregnant patient with acute pancreatitis are similar to those in nonpregnant patients. Intravenous hydration, nasogastric suction, enteric rest, and correction of electrolyte imbalance and of hyperglycemia are the mainstays of therapy. Careful attention to tissue perfusion, volume expansion, and transfusions to maintain a stable cardiovascular performance are critical. Gradual recovery occurs over 5 to 6 days.

2-45. The answer is c. (Freedberg, 5/e, pp 1482-1487.) The patient has the typical areas of involvement of seborrheic dermatitis. This common dermatitis appears to be worse in many neurological diseases. It is also very common and severe in patients with acquired immune deficiency syndrome (AIDS). In general, symptoms are worse in the winter. Pityrosporum ovale appears to play a role in seborrheic dermatitis and dandruff, and the symptoms improve with the use of certain antifungal preparations (e.g., ketoconazole) that decrease this yeast. Mild topical steroids also produce an excellent clinical response.

2-46. The answer is a. (Shuaib, p 33.) The head computed tomography (CT) scan is the mainstay of emergency department management of acute stroke. It is crucial to exclude intracranial hemorrhage prior to the potential administration of intravenous thrombolytic agents. A cerebral angiogram may play a role in the management of the acute stroke patient, particularly if there is evidence of cerebral or subarachnoid hemorrhage or if there exists a possibility of performing intraarterial thrombolysis, but CT scan is required first. T2-weighted MRI may also show ischemic and hemorrhagic injury, but infarction may not appear this quickly on MRI and hemorrhage may also be missed. MRI is also not as widely available as CT. In the absence of evidence of trauma at the time of this patient's fall, C-spine MRI and skull x-rays play no role in the management of this patient.

2-47. The answer is a. (Shuaib, pp 328-329.) Thrombolytic therapy with intravenous recombinant tissue plasminogen activator (rt-PA) has been shown in a large, multicenter randomized trial sponsored by the National Institutes of Health (NIH) to be of benefit to patients with acute ischemic stroke who can be treated early enough. The study demonstrated a statistically significant benefit from the use of rt-PA in the treatment of ischemic stroke patients who can be treated within 3 h of symptom onset. A total of 624 patients arriving at the hospital within 3 h of symptom onset underwent CT scan to exclude hemorrhagic stroke. Patients were randomized to receive either 0.9 mg/kg of rt-PA or placebo. At 3 mo, treated patients were at least 30% more likely to have minimal or no disability on several disability scales. Even with a symptomatic hemorrhage rate of 6.4% within 36 h among the active treatment patients, the mortality and disability among treated patients was less than that among placebo patients at 3 mo.

The overall acute neurologic deterioration even after accounting for early hemorrhages was the same in treated and placebo patients, indicating that the increased risk of hemorrhage with rt-PA therapy is offset by an increased risk of neurologic deterioration from progressing stroke, cerebral edema, and other causes in non-treated patients. The benefit of rt-PA was not limited to patients with cardioembolic or large vessel strokes, but also extended to patients with small-vessel strokes, who had a better prognosis.

2-48. The answer is a. (Schwartz, 7/e, pp 257, 522, 527, 617-621.) Squa-mous cell carcinoma occurs in people who have had chronic sun exposure, chronic ulcers or sinus tracts (draining osteomyelitis), and a history of radiation or thermal injury (Margolin's ulcer). It is more malignant than basal cell carcinoma, grows more rapidly, and metastasizes. It occurs more frequently in blondes and fair-skinned people. A radiation-induced carcinoma, or one arising in a burn scar, should not be treated with radiation therapy for fear of further damage.

2-49. The answer is e. (Holmes, 3/e, p 368. Fauci, 14/e, pp 1679-1681.) Currently available laboratory tests for hepatitis B include hepatitis B surface antigen (HBsAg), anti-HBs (antibody to hepatitis B surface antigen), immunoglobulin M (IgM) anti-HBc, immunoglobulin G (IgG) anti-HBc (antibodies to the core antigen), hepatitis B e antigen (HBeAg), and anti-HBe. Because HBcAg is sequestered within an HBsAg coat, HBcAg is not routinely detected in patients with hepatitis B. IgM Anti-HBc appears soon after the onset of infection and the detection of HBsAg, and precedes by many weeks detectable levels of anti-HBsAg. It generally disappears after 6 to 8 month. The presence of IgM is a marker for acute (less than 6 mo) hepatitis B. IgG anti-HBc appears somewhat later than the IgM and may persist for years. Elevated alanine aminotransferase (ALT) may be present both in the early and chronic phases of the disease. HBeAg may persist for years in patients with chronic disease, and is associated with high infectiv-ity. HBsAg remains detectable beyond 6 mo in chronic hepatitis B.

2-50. The answer is c. (Fauci, 14/e, pp 2030-2031, 2057, 2228-2229.) For the patient described in the question, the markedly increased calci-tonin levels indicate the diagnosis of medullary carcinoma of the thyroid. In view of the family history, the patient most likely has multiple endocrine neoplasia (MEN) type II, which includes medullary carcinoma of the thy-

Jaundice |

tALTl 1

HBeAg Anti-HBe

IgG Anti-HBc

/ \ Anti-HBs / j / lgMAnti-HBc\

Weeks after exposure (a)

12 24 36 46 60 Mtrfitns aft&r exposure (b)

Reprinted, with permission, from Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD et al (eds): Harrison's Principles of Internal Medicine, 14th ed. New York, McGraw-Hill, 1998.

roid gland, pheochromocytoma, and parathyroid hyperplasia. Pheochro-mocytoma may exist without sustained hypertension as indicated by excessive urinary catecholamines. Before thyroid surgery is performed on this patient, pheochromocytoma must be ruled out through urinary cate-cholamine determinations; the presence of such a tumor might expose the patient to a hypertensive crisis during surgery. The entire thyroid gland must be removed, because foci of parafollicular cell hyperplasia, a prema-lignant lesion, may be scattered throughout the gland. Successful removal of the medullary carcinoma can be monitored with serum calcitonin levels. Hyperparathyroidism, while unlikely in this patient, is probably present in his brother.

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