Malig neoplasm of ovrlp sites of rectum, anus and anal canal

This code signifies a cancerous tumor that originates in or spreads across multiple adjacent anatomical regions within the rectum, anus, and anal canal. It indicates that the primary site cannot be definitively assigned to a single subsite within this area due to the tumor's extensive involvement.

Apply this code when documentation clearly states a malignant neoplasm involving overlapping boundaries of the rectum, anus, and/or anal canal. This is appropriate when the tumor spans across these distinct anatomical areas, making it impossible to pinpoint a single primary origin site.

• Ensure the physician's documentation explicitly states "overlapping sites" or describes tumor involvement across multiple subsites of the rectum, anus, and anal canal.
• Do not use this code if the primary site can be clearly identified within a single subsite (e.g., rectum only, anal canal only).
• Always sequence this code as the primary diagnosis when it represents the reason for the encounter, followed by any relevant secondary diagnoses.