Answers

1. b—The spleen is a source of T lymphocytes, not a site of their filtration. Splenic filtration of spherocytes and other types of deformed red blood cells results in anemia and, often, jaundice. The spleen is the first defense against circulating malarial parasites. Splenectomy reduces the ability of the body to clear and opsonize encapsulated bacteria like Streptococcus pneumoniae. Overly aggressive, immunologically mediated splenic filtration of platelets results in idiopathic thrombocytopenic purpura.
    
2. d—The ilioinguinal nerve is responsible for providing sensation to the penis, upper scrotum, and inner thigh. Injury during inguinal herniorrhaphy, which can only occur at the external (not internal) ring, causes disturbing numbness in these areas. The ilioinguinal nerve is derived from the first lumbar nerve (not the femoral nerve) and is purely sensory (it has no motor function). It runs along the iliac crest and penetrates the transversus abdominus muscle at the external spermatic ring; its course is far anterior to the posteriorly located hypogastric vein.
    
3. a—The ratio of induced gastric ulcers to duodenal ulcers is about 2:1. There are some clinical situations in which both medication groups are needed; steroids can be added safely if prostaglandins or antisecretory agents are also administered. Nonsteroidal anti-inflammatory drugs cause bleeding and perforation. The agents have a minimal effect on gastric acid secretion and cause ulcers by interfering with gastric cytoprotective mechanisms.
    
4. a—There are excellent data which document that tamoxifen induces a more than 50% decrease in breast cancer incidence in women at genetic risk for this disease. The same does not hold true for ovarian cancer, the other lesion increased in frequency by this genetic abnormality. Tamoxifen is ineffective against ER-negative tumors and has a differential effect depending on the menopausal state of the woman. The most effective way to prevent breast cancer is by prophylactic mastectomy.
    
5. c—Laparoscopy can be more difficult in the morbidly obese, but it is certainly not contraindicated. If an upper limit of size is utilized, it is always a BMI of 35 kg/m² or greater. The determination of extent of resection in multifocal disease, either multilocular abscess or several areas of phlegmon, requires palpation and, thus, resection via laparoscopy cannot be performed safely. Laparoscopic colectomy takes longer to set up and perform than the open operation and is therefore contraindicated in emergency situations.
    
6. e—Recent studies have documented that caspofungin is at least as effective in this circumstance as amphotericin B, and it is safer and better-tolerated. Flucytosine induces resistance and must be used in combination therapy. Lysosomal amphotericin B is less nephrotoxic than the native compound, but it does induce renal and hepatic toxicity. Fluconazole is fungistatic, yet effective. Amphotericin B induces hypokalemia, which is surprising since it commonly causes renal failure; the electrolyte disturbance is unrelated to renal perfusion or clearance.
    
7. e—The dysgerminoma is a pure germ cell tumor, as is the male seminoma; these lesions behave in a very similar manner. As a germ cell tumor, dysgerminoma does not secrete estrogen. While this tumor often secretes hCG and, occasionally, LDH, it does not secrete CA-125, as do other ovarian malignancies. The tumor is bilateral in 10% to 15% of patients and is a relatively low-grade malignancy.
    
8. d—In this case, the old standard is still the best, with greater than 96% sensitivity and specificity. The most effective scintigraphic study is ¹³¹I-MIBG scanning. The plasma determinations are not specific, averaging only about 60% to 70%; thus, there are a number of false positives. Forty percent of pheochromocytomas are diagnosed by chemical studies in normotensive patients with adrenal incidentalomas. The usual provocative tests, when needed to establish the diagnosis, are glucagon infusion and clonidine suppression tests.
    
9. b—Bound bilirubin dissociates from albumin within the liver and is incorporated into hepatocytes, where conjugation goes on (not in the gallbladder). The conjugate is excreted into bile against concentration gradients in an energy-requiring process. Intestinal bacteria convert bilirubin to urobilinogen, not enterocytes. Eighty percent of bilirubin is produced by destruction of late phase, senescent erythrocytes.
    
10. e—While air can migrate from one serous cavity to another, it requires pressure. Spontaneous pneumothorax is not associated with increased pressure (at least until it becomes tension pneumothorax), so migration into the mediastinum is rare. Barotrauma, croup, and asthma all have elements of bronchoconstriction resulting in increased airway pressure, and migration of air into the mediastinum is fairly common. In Boerhaave’s syndrome, the esophagus can rupture into the mediastinum, causing pneumomediastinum.
     
11. e—Most patients with thoracic aneurisms are asymptomatic, and the vascular lesion is found incidentally on a chest radiograph. Back pain is generally unrelated to the aorta and is almost invariably muscular in origin. The other manifestations do occur, although uncommonly.
     
12. b—There are three scenarios by which diaphragmatic hernias present. The first and worst is with immediate respiratory failure; next is when symptoms appear within minutes to a couple of hours; the third scenario, and clearly the best, is when symptoms occur only after 24 or more hours, at which time, the infants have difficulty in feeding, intestinal obstruction, or pneumonia, but not respiratory failure. Despite much research and clinical trials including high-frequency oscillation ventilation, use of nitric oxide, early operation, etc, the average mortality rate for diaphragmatic hernia (60%–70%) has not changed. The major determinant of success or mortality is the extent of pulmonary hypertension.