Malignant carcinoid tumor of the rectum

This code signifies a cancerous tumor originating from neuroendocrine cells within the rectum, specifically characterized by its carcinoid nature. These tumors are typically slow-growing but can metastasize.

Use this code when documentation confirms a primary malignant carcinoid tumor located in the rectum. This diagnosis is typically established through biopsy and histopathological examination.

• Differentiate from benign carcinoid tumors (D3A.02x) or uncertain behavior (D3A.8).
• Ensure the pathology report explicitly states "malignant" and "carcinoid" for the rectal primary.
• Code any metastatic sites separately, following the primary malignancy.