C17
Non-Billable (Header)Malignant neoplasm of small intestine
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
What This Code Means
C17 is the ICD-10-CM diagnosis code for malignant neoplasm of small intestine. C17 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).
Header codes like C17 cannot be reported on claims directly — they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at C17's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C17 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Excludes 1 — Do NOT code together
- malignant carcinoid tumors of the small intestine (C7A.01)