C17.2
BillableMalignant neoplasm of ileum
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C17.2 an HCC code?
Yes. C17.2 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for C17.2
For C17.2 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C17.2 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C17.2 is the ICD-10-CM diagnosis code for malignant neoplasm of ileum. Cancer that develops in the ileum, which is the final and longest section of the small intestine. C17.2 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).
Under the CMS-HCC V28 risk adjustment model, C17.2 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, C17.2 mapped to the same category but with a base RAF weight of 0.973 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Document whether this is primary ileal cancer or secondary involvement; ileal cancers are uncommon. Because C17.2 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C17.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document whether this is primary ileal cancer or secondary involvement; ileal cancers are uncommon
- •Note any association with Crohn's disease or other predisposing conditions if present
Clinical Significance
Malignant neoplasm of the ileum affects the longest and most distal segment of the small intestine. The ileum is a relatively common site for carcinoid (neuroendocrine) tumors and lymphoma compared to other small bowel segments. Ileal cancers may present with obstruction, intussusception, or bleeding, and patients with Crohn disease affecting the ileum have an increased risk of malignancy. Accurate coding ensures risk adjustment reflects the complex care these patients require.
Documentation Requirements
- ✓Confirmed ileal location as the primary malignant site
- ✓Histological type (neuroendocrine/carcinoid tumors are common in this location)
- ✓Any history of Crohn disease or other predisposing inflammatory conditions
- ✓Stage of disease including mesenteric lymph node involvement
- ✓Distinction from Meckel diverticulum malignancy (C17.3)
Excludes 1 — Do NOT code together
- malignant neoplasm of ileocecal valve (C18.0)