Preguntas y Respuestas 1

CIRUGÍA GENERAL

A 55-year-old man presents to a physician with jaundice. Ultrasonography demonstrates a 5 cm mass in the head of the pancreas. Endoscopic retrograde cholangiopancreatography with cytologic sampling demonstrates cells with large hyperchromatic nuclei and a high nuclear/cytoplasmic ratio. A few small glands composed of these cells are also seen in the cytologic preparation. The overall prognosis for this man will be most similar to that of a patient with which of the following malignancies?

A. Adenocarcinoma of the breast

B. Adenocarcinoma of the colon

C. Adenocarcinoma of the esophagus

D. Adenocarcinoma of the prostate

E. Primary gastric lymphoma

Explanation:

The correct answer is C. The patient probably has pancreatic adenocarcinoma. This cancer carries one of the worst prognoses, with a 3.5% overall 5 year survival rate despite all attempts at aggressive management. The prognosis is also bleak with adenocarcinoma of the esophagus, with a 10% overall 5 year survival rate.

An 80-year-old man has low back pain. An x-ray of the lower back and pelvis shows sclerotic changes in the lower vertebrae and in focal areas throughout the pelvis. The radiologist's report states that the sclerotic changes may represent osteoarthritis; however, metastatic prostate cancer cannot be excluded. Which of the following is most cost-effective in the initial work-up of this patient?

A. Bone marrow aspirate and biopsy

B. Digital rectal exam

C. Prostate-specific antigen

D. Radionuclide bone scan

E. Serum alkaline phosphatase

Explanation:

If prostate cancer with osteoblastic (bone-forming) metastases to the vertebral column and pelvis were present in this patient (stage D disease), a digital rectal exam would be the most cost-effective initial step in the work-up. With advanced prostate cancer, the gland would very likely be enlarged and hard ("stony").

A 17-year-old male develops a painless, firm mass beneath the nipple of his left breast. The mass is mobile, and no fluid can be expressed from the breast. The right breast is normal to examination. Which of the following conditions does this mass most likely represent?

A. Fibrocystic changes

B. Gynecomastia

C. Intraductal papilloma

D. Invasive duct carcinoma

E. Invasive lobular carcinoma

Explanation:

The correct answer is B. The most common breast mass in men, especially under 25 years of age, is gynecomastia-a benign proliferation of ductal and stromal elements of the breast. It is generally an idiopathic condition, probably related to pubertal hormonal changes.

A neonate develops bile-stained vomiting and progressive abdominal distention, and does not pass meconium over the first two days of life. The anus is patent, and the bowel loops are palpable. Plain radiograph shows bubbly meconium in the right lower quadrant. No localized areas of constriction or other abnormalities are noted.

Which of the following is most likely etiologically related to this infant's condition?

A. Cystic fibrosis

B. Hirschsprung's disease

C. Meckel's diverticulum

D. Omphalocele

E. Polycystic kidney disease

Explanation:

The correct answer is A. The baby has meconium ileus, which is a manifestation of cystic fibrosis due to the abnormally viscid pancreatic secretions which "get stuck" in the small bowel. Meconium ileus can cause gut perforation with peritonitis and intraperitoneal calcifications (that may be visible on plain film). Meconium ileus complicated by intestinal perforation or formation of fistulas to the bladder or vagina must be treated surgically.

A 69-year-old woman is brought to the emergency room after falling off a step stool and fracturing her hip. Her past medical history is significant for several bouts of pneumonia during the past year. Laboratory results indicate a normal white blood cell count, but platelets are decreased, and the erythrocyte sedimentation rate (ESR) is elevated. X-rays reveal multiple lytic bone lesions. Serum electrophoresis demonstrates an M-protein spike.

Which of the following is the most likely diagnosis?

A. Chronic lymphocytic leukemia

B. Monoclonal gammopathy of uncertain significance

C. Multiple myeloma (plasma cell myeloma)

D. Plasmacytoma

E. Waldenström's macroglobulinemia

Explanation:

The correct answer is C. The patient is suffering from multiple myeloma, a neoplastic proliferation of Plasma cells (or their precursors) found within the bone marrow. These malignant cells are responsible for the production of excessive amounts of immunoglobulin (usually IgG or IgA), producing an M- protein spike, and increasing the ESR. The decreased platelet count probably reflects infiltration of the bone marrow by mieloma cells. It is not unusual for patients with malignant myeloma to have recurring bacterial infections, particularly pneumococcal pneumonia, because the overall production of normal immunoglobulins of all isotypes is decreased. Lytic bone lesions due to infiltration by myeloma cells may lead to pathological fractures.

A 65-year-old woman presents with a 30-lb weight loss and malaise. Cancer is suspected. Which of the following is the correct list, starting with the most prevalent, of the three most common causes of cancer in women?

A. Breast, lung, colon and rectum

B. Breast, uterus, lung

C. Colon and rectum, lung, ovary

D. Lung, breast, ovary

E. Ovary, uterus, lung

Explanation:

The correct answer is A. The correct female incidence sequence is breast (32%), lung (13%), and colon and rectum (13%). The two major causes of cancer death in women are lung (23%) and breast (18%). In men, the incidence sequence is prostate (32%), lung (16%), and colon and rectum (12%). The two leading causes of male cancer deaths are lung (33%) and prostate (13%).

A 52-year-old woman has recently undergone a breast resection for carcinoma. Based on the statistics for breast cancer incidence, which of the following types of carcinoma does this patient most likely have?

A. Colloid (mucinous)

B. Invasive ductal

C. Invasive lobular

D. Medullary

E. Metastatic bronchogenic

Explanation:

The correct answer is B. Invasive ductal carcinoma is the most likely candidate. Of the various types of breast adenocarcinoma, invasive ductal carcinoma is by far the most common variant, accounting for Approximately 75% to 80% of all invasive breast carcinomas. Invasive ductal carcinoma develops from epithelial cells of the terminal duct. Histologically, it is composed of small, glandular, ductlike structures, lined by variably Anaplastic cells.

A 24-year-old woman gives birth to an apparently normal infant. The neonate begins feeding well by the second day, then at ten days, suddenly develops gastrointestinal obstruction. Which of the following is the most likely cause of this presentation?

A. Adhesions

B. Congenital pyloric stenosis

C. Hirschsprung's disease

D. Intussusception

E. Volvulus

Explanation:

The correct answer is D. All of the conditions listed can cause gastrointestinal obstruction, but the clinical presentation is most suggestive of intussusception. In intussusception, there is telescoping of one bowel segment into another, more distal segment. The disorder is relatively common in infants and children due to the poor support offered by their thin mesentery. Intussusception produces intestinal obstruction, and it may produce bowel ischemia or infarction by trapping mesenteric vessels along with the affected segment. In some cases, the intussusception may be reduced by diagnostic barium enema.

A 54-year-old man presents with a chief complaint of "burning" abdominal pain in the epigastric region. Endoscopy demonstrates a well-defined, regular gastroesophageal junction located 3 cm above the Esophageal hiatus in the diaphragm. Biopsy of the distal side of the junction demonstrates normal gastric mucosa. This lesion is best classified as which of the following?

A. Achalasia

B. Esophageal ring

C. Esophageal web

D. Paraesophageal hernia

E. Sliding hernia

Explanation:

The correct answer is E. This patient has a sliding hiatal hernia, which is the most common (90%) form of hiatal hernia. This condition is frequently associated with gastric reflux.

Which of the following locations is most likely for the development of carcinoma in a 32-year-old baseball player who has chewed tobacco for 15 years?

A. Floor of the mouth

B. Lower lip

C. Tongue

D. Tonsils

E. Upper lip

Explanation:

The correct answer is B. Oral cancer is most strongly related to tobacco chewing, with weaker associations with cigarette smoking, pipe smoking, and alcohol use. Oral cancers tend to occur on the lower lip (40%; choice B), tongue (20%; choice C), floor of the mouth (15%; choice A), with other oral sites (choices D and E) being less common. They are usually squamous cell carcinomas and unlike their skin counterparts, frequently cause both extensive morbidity and mortality.

A 35-year-old man who recently traveled to a third world country develops chronic, severe dysentery. Colonoscopy demonstrates ulceration of the cecum, and a cecal biopsy reveals 15-to-40 micron amoebae with ingested erythrocytes and small nuclei with distinctive tiny central karyosomes. Which of the following organisms is the most likely culprit?

A. Acanthamoeba sp.

B. Balantidium coli

C. Entamoeba histolytica

D. Giardia lamblia

E. Naegleria fowleri

Explanation:

The correct answer is C. Entamoeba histolytica is the usual cause of intestinal amebiasis, and has the microscopic features described in the question stem. A particularly helpful (but not always present) feature of this organism is the presence of ingested red blood cells within the amoebae. These amoebae cause flask-shaped ulceration of the intestinal mucosa and submucosa, with a particular propensity for involving the cecum and ascending colon.

An endocrinologist examines a patient suspected of having Riedel thyroiditis. Which of the following findings on physical examination would best help confirm the diagnosis?

A. Eyeball protrusion

B. Massive soft thyroid gland

C. Single large thyroid nodule

D. Very tender and painful thyroid

E. "Woody" thyroid gland

Explanation:

The correct answer is E. Riedel thyroiditis, also called ligneous (rocklike) stroma, is a rare form of chronic thyroiditis characterized microscopically by a marked fibrous reaction that destroys most or all of the thyroid gland and may involve adjacent structures. The etiology is unknown. Clinically, this disease tends to affect middle-aged and older, mostly female patients and causes the thyroid to have a firm "woody" texture. It may be clinically mistaken for a neck malignancy and can cause symptoms of stridor, dyspnea, dysphasia, laryngeal nerve paralysis, or hypothyroidism.

A 52-year-old male presents with epigastric pain that improves with meals. Endoscopy demonstrates a 2 cm ulcerated area located 3 cm distal to the pyloric junction. Basal acid output is within normal limits. Which of the following is most likely to have made the strongest contribution to the development of this disease?

A. Aspirin use

B. Chronic antacid use

C. Drinking alcohol

D. Helicobacter pylori infection

E. Smoking

Explanation:

The correct answer is D. The patient has a duodenal peptic ulcer. The strongest risk factor for duodenal peptic ulcer is Helicobacter pylori infection, which is found in almost 100% of these cases (contrast to 70% infection rate in gastric peptic ulcer). The basal acid output is normal in many patients with duodenal ulcer.

A 32-year-old African American female presents with pelvic pain, low back pain, and a sensation of "pulling" or "stretching" in her groin. Bimanual examination reveals a firm mass in the right adnexa. An ultrasound examination reveals the presence of fluid in the abdominal cavity and the right thoracic cavity. Which of the following conditions is most strongly suggested by this patient's presentation?

A. Ectopic pregnancy

B. Endometrial implant

C. Ovarian fibroma

D. Pelvic inflammatory disease

E. Uterine leiomyoma

Explanation:

The correct answer is C. Meigs syndrome is the unusual combination of hydrothorax (often right sided), ascites, and an ovarian tumor (often a benign fibroma). Low back pain and a stretching or pulling sensation are characteristic of ascites in some patients (ascites can also be asymptomatic). The etiology of the fluid accumulation in Meigs syndrome remains a mystery.

A 63-year-old African-American male presents with vague complaints of abdominal and back pain, malaise, nausea, and weakness, which have been present for 3 or 4 months. Review of systems reveals a 15 pound weight loss, occasional vomiting, and several episodes of unilateral leg swelling, which have involved both legs at different times. These findings are most consistent with which of the following diagnoses?

A. Pancreatic cancer

B. Primary sclerosing cholangitis

C. Pyelonephritis

D. Reflux esophagitis

E. Splenic infarction

Explanation:

The correct answer is A. Pancreatic carcinoma often presents with vague abdominal, back, and gastrointestinal complaints; and physical examination is generally unrevealing. The tremendous weight loss is very suspicious for carcinoma, and the migrating thrombophlebitis (Trousseau's sign) is extremely helpful in making the diagnosis, which should be confirmed with ultrasonography or CT. Although any carcinoma can elicit migratory thrombophlebitis, it is mostly associated with tumors of the pancreas, lung, and colon.