Malignant neoplasm of overlapping sites of colon

This code signifies a primary malignant tumor that originates in, or extends across, two or more adjacent anatomical sub-sites within the colon, where the point of origin cannot be definitively assigned to a single sub-site. This includes cases where the tumor bridges areas like the ascending colon and transverse colon, or the sigmoid colon and rectum, making a more specific site impossible to determine.

Apply this code when documentation clearly indicates a colorectal malignancy involving multiple contiguous segments of the colon, and the precise primary site cannot be localized to a single, distinct anatomical region. This is common in advanced or large tumors that have spread beyond their initial origin within the colon.

• Ensure the physician's documentation explicitly states involvement of "overlapping sites" or describes a tumor spanning multiple contiguous colon segments without a single identifiable primary.
• Avoid using this code if the tumor's origin can be clearly attributed to a single, specific colon sub-site (e.g., ascending colon, transverse colon).
• Always sequence this code as the primary diagnosis when it represents the reason for the encounter or treatment.