Histology Coding Rules: Colon/Rectum
Multiple Tumors with Different Behaviors in Same Organ Reported as Single Primary
Code the histology of the invasive tumor when one lesion is in situ and the other is invasive
Example: 2 separate sigmoid polyps
adenocarcinoma in situ in polyp 8210/2
adenocarcinoma in polyp stalk 8210/3
Answer: 8210/3 Adenocarcinoma in polyp
This rule is used when there are multiple tumors with different behaviors in the same organ reported as a single primary. Code the histology of the invasive tumor when one lesion is in situ and the other is invasive.
Example: There are two polyps in the sigmoid colon. The histology for both polyps is adenocarcinoma in a polyp, but the behavior for the first polyp is in situ and the behavior for the second polyp is invasive. This is one primary because the lesions are in the same subsite and have the same histology, and the invasive histology, adenocarcinoma in a polyp (8210/3), is recorded.