Histology Coding Rules: Colon/Rectum
6. Code all other multiple tumors with different histologies as multiple primaries
Example: Sigmoid colon, 2 lesions
Answer: 2 primary sites; complete abstract for each one
Rule 6: Code all other multiple tumors with different histologies as multiple primaries. If there are multiple tumors in the same segment of the colon with different histologies and they don’t meet the circumstances described in the previous rules, consider the tumors separate primaries and complete multiple abstracts.
Example: There are two lesions in the sigmoid colon. The first lesion is mucinous adenocarcinoma, and the second lesion is malignant lymphoma. The histologies are different and none of the rules for multiple tumors determined to be a single primary apply. The lesions are separate primaries and two abstracts should be completed.