C24.8
BillableMalignant neoplasm of overlapping sites of biliary tract
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C24.8 an HCC code?
Yes. C24.8 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 C24.8
For C24.8 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 C24.8 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C24.8 is the ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of biliary tract. Cancer involving multiple overlapping sites within the biliary tract system, including bile ducts and related structures. C24.8 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, C24.8 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, C24.8 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.
Use this code when the tumor involves more than one distinct site of the biliary tract. Because C24.8 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 C24.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code when the tumor involves more than one distinct site of the biliary tract
- •Document all involved sites clearly in the medical record to support the overlapping sites designation
Clinical Significance
Overlapping sites of the biliary tract indicates a malignant tumor spanning multiple structures within the biliary system (gallbladder, cystic duct, common bile duct, hepatic ducts, ampulla). This code reflects more extensive disease that often indicates advanced cancer with involvement of multiple biliary structures. These patients typically have limited surgical options and may require palliative stenting or bypass procedures for biliary obstruction.
Documentation Requirements
- ✓Documentation confirming involvement of two or more distinct biliary tract structures
- ✓Identification of the specific structures involved
- ✓Histological type
- ✓Stage of disease and extent of biliary involvement
- ✓Assessment of resectability