A pathologist evaluates a colonic polyp showing dysplastic crypts surrounded by inflamed lamina propria that has NOT breached the muscularis mucosae. According to the WHO 2019 digestive tumor classification, how should this lesion be staged?

• A pT1 — superficially invasive adenocarcinoma
• B pTis — high-grade intramucosal carcinoma (in situ) ✓
• C pT2 — invasion of muscularis propria
• D High-grade dysplasia; staged only after resection of the entire lesion

Explanation

In colorectal neoplasia, the WHO 2019 classification designates intramucosal carcinoma (invasion into lamina propria or muscularis mucosae but not through it) as pTis because metastatic potential is negligible given the absence of lymphatics in the colonic mucosa above the muscularis mucosae. pT1 requires submucosal invasion. pT2 denotes muscularis propria invasion. Calling it 'high-grade dysplasia' is the older terminology superseded by the WHO 2019 classification.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.