A 55-year-old man was referred to surgeon because he has become increasingly constipated over the last 2 months. This has occurred despite attempts to increase fiber in his diet and to markedly increase his physical activity. Laxatives have been mostly ineffective. On fuher questioning, the man repos that he has twice seen fresh blood on his stools, which he attributed to hemorrhoids. He has also noticed a sense of fullness and discomfo in his lower left abdominal quadrant, but attributed these findings to his constipation. Digital examination is negative. Colonoscopy demonstrates an area of stricture with surface ulceration 10 cm above the anal verge. The distal colon is surgically resected. Pathologic examination demonstrates a napkin-ring lesion with marked thickening of the mucosal layer of the rectum. On cross- section, the lesion is seen to extend through the rectal muscle and into, but not through, the adjacent serosal adipose tissue. Fuher evaluation fails to demonstrate the patient’s disease in either lymph nodes or distant sites. This patient’s disease would be staged as which of the following?

**Core Concept**
The question requires staging of a rectal cancer based on its local extent and spread. The TNM staging system is used to classify the extent of cancer spread and guide treatment decisions.

**Why the Correct Answer is Right**
The patient has a rectal cancer with a "napkin-ring lesion" indicating a circumferential tumor that has invaded through the muscularis propria but not through the serosa, which is a characteristic feature of T3 tumors. The absence of lymph node involvement and distant metastases indicates that the cancer has not spread to regional lymph nodes (N0) or distant sites (M0). Therefore, the correct staging is T3N0M0.

**Why Each Wrong Option is Incorrect**
**Option A:** This staging would be incorrect because it implies lymph node involvement (N1), which is not supported by the pathologic examination.
**Option B:** This staging would be incorrect because it implies distant metastases (M1), which is not supported by the further evaluation.
**Option C:** This staging would be incorrect because it implies a more extensive tumor invasion through the serosa (T4), which is not supported by the pathologic examination.

**Clinical Pearl / High-Yield Fact**
When evaluating rectal cancer, it's essential to remember that the depth of tumor invasion (T stage) is more important than the size of the tumor in determining prognosis and treatment.

**Correct Answer:** C. T3N0M0.

✓ Correct Answer: C. Duke's classification B2