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Chapter 10: Pathology of the Gastrointestinal Tract

A 24-year-old woman presents to her primary care physician with a 1-month history of frequent, loose stools that contain blood and mucus. A colonoscopy is performed and shows granularity and erythema extending from the rectum to the splenic flexure. Which of the following is the most likely diagnosis?

A. Diverticular disease associated colitis

B. Crohn disease

C. Diversion colitis

D. Ulcerative colitis

E. Strongyloides infection

Answer: D

Explanation: Mucosal inflammation that begins at the anorectal junction and extends proximally in a contiguous manner is classic for ulcerative colitis.

Which of the following histologic findings IS NOT a typical finding in chronic colitis?

A. Crypt architectural disarray

B. Absence of ganglion cells

C. Paneth cell metaplasia

D. Basal plasmacytosis

E. Crypt branching

Answer: B

Explanation: An absence of ganglion cells within the submucosa and myenteric plexus is a diagnostic finding in Hirschsprung disease.

Which of the following pathologic findings is paired with the correct disease?

A. Epithelioid granulomas: Ulcerative colitis

B. Contiguous inflammation beginning at the anorectal junction: Crohn disease

C. Transmural inflammation: Crohn disease

D. Fistulas: Ulcerative colitis

E. Inflammation restricted to the mucosa: Crohn disease

F. Strictures: Ulcerative colitis

Answer: C

Explanation: Crohn disease is characterized by skip lesions, transmural inflammation, fistulas, strictures, and epithelioid granulomas. Ulcerative colitis is characterized by mucosal inflammation beginning at the anorectal junction and extending a variable distance proximally in a contiguous manner.

A colonoscopy is performed on a 42-year-old man to investigate rectal bleeding. A 4 cm ascending colon mass is identified, and a biopsy confirms the presence of invasive colonic adenocarcinoma. An immunohistochemical stain for MSH6 (a mismatch repair protein) demonstrates a loss of expression in the tumor. The patient’s family history is notable for colon cancer in multiple family members. Which of the following conditions predisposed this patient to developing colon cancer?

A. Lynch syndrome

B. Dysplasia arising in ulcerative ...

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