Diverging Ways of Determining Depth of Invasion in Pedunculated pT1 Colon Carcinomas

• Published in: Archives of pathology & laboratory medicine (1976) Vol. 144; no. 6; p. 671
• Main Authors: de Freitas Pinheiro, Junior, Nathanael, da Silva, Nataly Dantas Fortes
• Format: Journal Article
• Language: English
• Published: United States College of American Pathologists 01-06-2020
• Subjects: Colon; Colon cancer; Colorectal cancer; Endoscopy; Lymph nodes; Lymphatic system; Metastases; Metastasis; Pathology; Polyps; Rectum; Surgeons; Systematic review; Tumors
• ISSN: 0003-9985; 1543-2165; 1543-2165
• DOI: 10.5858/arpa.2019-0568-LE

The widely accepted cutoff of 1.0 mm (1000 gm) is based on papers that measured depth of invasion as the distance from the deepest tumor cell to the Haggitt line (Haggitt level 3 or 4 only).2,3 However, depth of invasion may also be measured from the muscularis mucosae or, in its absence, from tumor surface.4 The College of American Pathologists template5 (August 2018) and the paper by Hagen and Farooq1 suggest this latter method, but refer to the 1.0-mm cutoff value, based on the same systematic review.6 If measured from the Haggitt line, the risk of lymph node metastasis in pedunculated tumors <1.0 mm deep2,3 is equivalent to that found in tumors <2.0 mm if measured from the muscularis mucosae.4 Apples and oranges have been mixed. [...]we feel that including measurements obtained with both methods in the final report, with an accompanying note explaining the differences in those methods, benefits our patients and our clinical and surgical colleagues. Pedunculated polyps generally have a low risk of lymph node metastases, and, as you point out, some studies in the literature have measured depth of invasion in pedunculated polyps from the Haggitt line (ie, polyp neck).1,2 The Japanese Society for Cancer of the Colon and Rectum 2016 guidelines advocate measuring depth of invasion from the muscularis mucosae when intact regardless of the polyp configuration and measuring from the Haggitt line only in pedunculated lesions with "tangled muscularis mucosae.