C17.8
BillableMalignant neoplasm of overlapping sites of small intestine
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C17.8 an HCC code?
Yes. C17.8 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 C17.8
For C17.8 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 C17.8 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C17.8 is the ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of small intestine. Cancer involving multiple overlapping sites within the small intestine rather than being limited to one section. C17.8 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, C17.8 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, C17.8 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.
Specify which sections of small intestine are involved (duodenum, jejunum, ileum) in documentation. Because C17.8 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 C17.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Specify which sections of small intestine are involved (duodenum, jejunum, ileum) in documentation
- •Overlapping involvement suggests more extensive disease requiring comprehensive staging
Clinical Significance
Overlapping sites of the small intestine indicates a malignant tumor spanning multiple segments (duodenum, jejunum, ileum), reflecting more extensive disease. These tumors are generally associated with a worse prognosis due to their size and extent, often requiring more extensive surgical resection. Accurate coding of overlapping versus single-site disease is important for both risk adjustment and clinical research tracking of advanced small bowel malignancies.
Documentation Requirements
- ✓Documentation confirming the tumor involves two or more distinct segments of the small intestine
- ✓Identification of the specific segments involved
- ✓Histological type
- ✓Confirmation this is a single primary tumor spanning segments, not multiple separate primaries
- ✓Stage of disease and extent of resection