Malignant carcinoid tumor of the appendix

This code identifies a primary neuroendocrine tumor originating in the appendix, characterized by its malignant nature. These tumors, also known as carcinoids, arise from enterochromaffin cells and can secrete various hormones, though they are often asymptomatic until advanced stages.

Apply this code when documentation confirms a malignant carcinoid tumor specifically located in the appendix. This diagnosis is typically established through histopathological examination of an appendectomy specimen or biopsy. Use this code as the primary diagnosis when the appendiceal carcinoid is the reason for the encounter.

• Differentiate from benign appendiceal carcinoids, which are coded differently.
• Ensure documentation specifies "malignant" to support this code; otherwise, a benign or uncertain behavior code may be more appropriate.
• If metastasis is present, sequence the primary appendiceal carcinoid first, followed by codes for the secondary malignant neoplasms.