Adenocarcinoma 1

Question

Vignette: A 52-year-old woman presents to her primary care physician complaining of intermittent rectal bleeding and changes in her bowel habits over the past few months. She denies any abdominal pain, weight loss, or changes in her appetite. Her past medical history is unremarkable, and she has no known family history of cancer. She underwent menopause at age 50 and has not had any postmenopausal bleeding. She has never had a colonoscopy. On physical examination, her abdomen is soft and non-tender, with no palpable masses. Rectal examination reveals occult blood. A colonoscopy is performed and reveals a single, non-obstructing mass in the ascending colon. Biopsy of the mass is performed, and pathology reveals adenocarcinoma.

Question: Which of the following pathologic descriptions best characterizes this patient's cancer?

Choices

A) Well-differentiated squamous cell carcinoma

B) Poorly differentiated adenocarcinoma

C) Moderately differentiated adenocarcinoma

D) Well-differentiated adenocarcinoma

E) Poorly differentiated squamous cell carcinoma

Answer

D) Well-differentiated adenocarcinoma

Explanation

The majority of colon cancers are adenocarcinomas. These tumors arise from the glandular epithelial cells lining the colon and rectum. The degree of differentiation refers to how closely the cancer cells resemble normal cells from the same tissue type. Well-differentiated cancers closely resemble the normal tissue of origin, moderately differentiated cancers somewhat resemble the normal tissue, and poorly differentiated cancers bear little resemblance to the normal tissue. This patient's cancer was described as a non-obstructing mass, suggesting that it has not invaded deeply into the colon wall or caused significant disruption of the bowel lumen. This, combined with her lack of symptoms such as abdominal pain or weight loss, suggests that the cancer is likely well-differentiated.