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SEER Inquiry System - Report
Produced: 05/24/2026 2:25 PM
Question 20150031
Inquiry Details
References:
#1: 2007 MP/H Rules. Colon
#2: WHO Class Digest System Tumors, 141. 2010
Question:
MP/H Rules/Multiple primaries--Colon: This is an unusual case of multifocal colon cancer. The case is staged pT4b,N1b. Per our MP rules, this will be 4 separate primaries. Would this be an exception to the rules; if not now, possibly in future versions of the MP rules for colon cancer? See discussion.
Discussion:
The path report reads: COMMENT: There is multifocal involvement throughout both bowel segments which combined represent a subtotal colectomy procedure. There are at least 11 tumors, all of which are histologically similar. Given the unusual gross appearance, a representative portion of the largest mass (hepatic flexure) was forwarded to _____ for flow cytometric evaluation. There is chronic active colitis in the background suggestive of idiopathic inflammatory bowel disease, specifically ulcerative colitis. However, no dysplasia is seen in multiple random sections of grossly benign large bowel. ADDENDUM from expert gastroenterologist: The carcinomas are poorly differentiated without specific histologic features but are consistent with colon primaries. These findings are consistent with an MLH1-deficient carcinoma. Given the background chronic active colitis consistent with ulcerative colitis, this likely represents colitis-associated neoplasia which can be associated with multifocality.
Answer:
This unusual case of multifocal colon cancer is not an exception to the MP/H rules currently.
The current WHO classification for colon tumors mentions ulcerative colitis (UC) associated colorectal cancers and states they are often multiple. This will be discussed for the next version of the MP/H rules.
