Malignant neoplasm of rectosigmoid junction

This code signifies a primary cancerous tumor originating at the anatomical border between the rectum and the sigmoid colon. This malignancy involves uncontrolled cell growth within the tissues of this specific colorectal region.

Apply this code when documentation clearly states a primary malignant neoplasm located at the rectosigmoid junction. This diagnosis is typically confirmed through biopsy and imaging studies, with pathology reports specifying the tumor's origin at this site.

• Differentiate from malignant neoplasms of the rectum (C20) or sigmoid colon (C18.7) when the tumor crosses the junction.
• Ensure the documentation specifies "primary" malignancy; secondary or metastatic lesions are coded differently.
• Review pathology reports carefully to confirm the exact anatomical site of origin.