A 46-year-old man comes to the office due to abdominal discomfort and diarrhea.  The symptoms began 6 months ago, and he has now developed significant weight loss.  The patient does not use tobacco or alcohol.  Intestinal biopsy is performed, and a periodic acid–Schiff (PAS) stained section is shown in the image below:

Which of the following is the most likely cause of this patient’s symptoms?

A 50-year-old woman comes to the office for a preventive examination.  She feels well and has no ongoing symptoms.  Medical and family histories are unremarkable.  The patient does not use tobacco or alcohol.  Blood pressure is 132/76 mm Hg and pulse is 72/min.  BMI is 25 kg/m2.  Physical examination is normal.  The patient is up to date on breast and cervical screenings but has not undergone colon cancer screening.  She is referred for colonoscopy, during which a single colon polyp is discovered.  The polyp is removed and sent for microscopic examination.  Which of the following pathologic findings would be associated with the greatest risk of malignant transformation?

A 58-year-old man with a history of chronic liver disease secondary to hepatitis C infection comes to the office due to progressive fatigue and abdominal discomfort.  He has no other medical conditions, and a recent colonoscopy was normal.  Physical examination shows ascites and jaundice.  Ultrasonography of the abdomen reveals a solid mass within the liver parenchyma.  Surgical resection of the liver lesion is performed.  Microscopy reveals large cells with prominent nucleoli arranged in thickened plates as shown below.

Which of the following serum markers would be most useful for monitoring this patient for disease recurrence?

A 22-year-old man is brought to the emergency department with abdominal pain that started around his belly button, then moved to the right lower abdominal quadrant.  After initial evaluation, laparotomy is performed, and the surgical specimen is shown in the image below:

Which of the following most likely initiated this patient’s condition?

A 21-year-old man comes to the office due to yellow discoloration of his eyes after a hiking trip.  The patient had a similar episode 2 years ago after fasting for a couple of days.  Vital signs are within normal limits.  Examination shows scleral icterus; there is no hepatosplenomegaly.  Laboratory findings are as follows:

Which of the following is the most likely cause of this patient’s jaundice?

A 65-year-old man comes to the office due to progressive weight loss, jaundice, and anorexia over the last 3 months. His urine has been dark and his stools have been pale. The patient has no prior medical conditions and takes no medications. He has smoked a pack of cigarettes a day for 40 years. He drinks 2 cups of coffee every day and 1 or 2 glasses of wine on most nights. He used illicit drugs for 2 years when he was in his teens but has used none since. The patient has a sedentary lifestyle and frequently consumes red and processed meats. Vital signs are within normal limits. BMI is 28 kg/m2. Physical examination shows scleral icterus. The chest is clear to auscultation and percussion. Abdominal examination shows an enlarged but nontender gallbladder. There is no ascites. Which of the following is the strongest factor predisposing to this patient’s current condition?

A 50-year-old man is scheduled to undergo a colonoscopy for routine colorectal cancer screening.  He has no abdominal pain, gross blood in the stool, constipation, change in stool caliber, or unintentional weight loss.  He also has no family history of colon cancer.  The procedure is uncomplicated, but the patient is found to have a small mucosal lesion (~1 cm) in his sigmoid colon.  The lesion is biopsied and its histology is shown in the image below.

The pathogenesis of this patient’s lesion most likely began with a mutation involving which of the following genes?

A 63-year-old man comes to the office due to several months of dysphagia, fatigue, occasional chest discomfort, and indigestion.  He has a history of hypertension and takes amlodipine.  The patient smokes 1 or 2 cigars daily.  His blood pressure is 140/80 mm Hg.  Physical examination is normal.  An endoscopic evaluation with esophageal biopsy is performed.  The histopathology of the specimen is shown in the image below.

Which of the following is the most likely cause of this patient’s dysphagia?

A 59-year-old man is evaluated in the clinic for recent unintentional weight loss.  He says, “My pants are fitting a lot looser than usual.”  The patient also has epigastric discomfort after meals with occasional nausea.  He reports that food is not as appetizing as it used to be.  He has no known medical conditions and takes no medications.  The patient’s father has a history of peptic ulcer disease.  Upper endoscopy shows a lesion in the stomach that is biopsied; a histologic section is shown below:

This patient’s lesion is most likely to demonstrate which of the following gross findings?

A 72-year-old woman comes to the office for follow-up of chronic abdominal pain.  She has had several episodes of left lower quadrant pain requiring hospitalization.  Despite treatment, her symptoms continue to recur.  Elective surgery is performed and a segment of resected and opened sigmoid colon is shown below.

Which of the following most likely contributed to this patient’s condition?

A 32-year-old man is being evaluated due to mild abdominal discomfort and anorexia.  He recently consumed large amounts of alcohol at a holiday party.  A liver biopsy is performed, and light microscopy findings are shown in the image below:

Which of the following metabolic changes most likely contributed to the development of this patient’s biopsy findings?

A 21-year-old woman is hospitalized for elective subtotal colectomy with ileo-rectal anastomosis due to abnormal colonoscopic findings.  She underwent screening colonoscopy because of family history of colon cancer.  Her maternal grandfather died of metastatic colon cancer, and her mother was also recently diagnosed with colon cancer.  The patient has no other medical problems, takes no medications, and does not use tobacco, alcohol, or illicit drugs.  The surgery is performed with no operative complications.  Numerous lesions are present throughout the resected colon, some of which are shown in the histopathology exhibit below.

Genetic testing is most likely to reveal a germline mutation resulting in which of the following effects?

A 48-year-old man comes to the emergency department due to 3 days of progressively worsening retrosternal burning chest pain, dysphagia, and odynophagia.  His medical problems include hypertension and end-stage renal disease.  He underwent cadaveric renal allograft transplantation 8 months ago.  The patient’s temperature is 38.3 C (101 F), blood pressure is 130/80 mm Hg, and pulse is 94/min.  His BMI is 31 kg/m2.  The oral mucosa is pink and moist without ulcerations.  Cardiopulmonary examination is normal.  The abdomen is soft with mild epigastric tenderness.  The patient’s leukocyte count is 4,200/mm3.  An esophagogastroduodenoscopy demonstrates linear, shallow ulcerations in the lower esophagus.  Which of the following is most likely to be seen on esophageal biopsy?

A 19-month-old boy is brought to the emergency department with severe abdominal pain and vomiting.  On initial evaluation, rebound and guarding are present.  Laparotomy is performed, and a portion of the intestine is resected; the gross specimen is shown in the image below:

Which of the following best describes the underlying pathologic process that led to this patient’s condition?

A 14-month-old girl is brought to the office due to a 2-month history of diarrhea.  Her parents report that she has 3-5 loose, nonbloody bowel movements daily with occasional episodes of vomiting.  She was breastfed exclusively until age 9 months and has since had a well-varied diet including whole milk, fruits, vegetables, bread, and meats.  However, the girl has been less interested in food over the past several weeks.  There is no history of travel or contacts with similar symptoms.  On physical examination, the patient appears well but has lost 1.1 kg (2.5 lb) in the last 2 months.  After laboratory evaluation, duodenal biopsy findings are shown in the exhibit.  Which of the following would most likely improve this patient’s symptoms?