C24.0
BillableMalignant neoplasm of extrahepatic bile duct
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C24.0 an HCC code?
Yes. C24.0 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 C24.0
For C24.0 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 C24.0 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C24.0 is the ICD-10-CM diagnosis code for malignant neoplasm of extrahepatic bile duct. Cancer that starts in the bile ducts outside the liver. These ducts carry bile from the liver and gallbladder to the small intestine. C24.0 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, C24.0 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, C24.0 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.
Distinguish from intrahepatic bile duct cancer (C22.1) which occurs within the liver. Because C24.0 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 C24.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish from intrahepatic bile duct cancer (C22.1) which occurs within the liver
- •Document the specific location and stage of the tumor for accurate coding and treatment planning
Clinical Significance
Malignant neoplasm of the extrahepatic bile duct (extrahepatic cholangiocarcinoma) includes cancers of the common hepatic duct, common bile duct, and cystic duct outside the liver parenchyma. This includes the clinically important Klatskin tumor (perihilar cholangiocarcinoma), which occurs at the hepatic duct bifurcation. These cancers are significant for risk adjustment because they are aggressive, often unresectable at presentation, and require complex multidisciplinary management.
Documentation Requirements
- ✓Documentation confirming extrahepatic bile duct as the primary tumor location
- ✓Specific location within the extrahepatic ducts (perihilar vs distal)
- ✓Bismuth-Corlette classification for perihilar tumors if applicable
- ✓Histological confirmation of carcinoma
- ✓Stage of disease and resectability assessment
Commonly Confused Codes
- •C22.1 — Intrahepatic bile duct carcinoma: intrahepatic cholangiocarcinoma occurs within the liver; C24.0 is for ducts outside the liver
- •C24.1 — Ampulla of Vater: the ampulla is the distal opening; cancers of the ampulla have different prognosis and treatment
- •C23 — Gallbladder cancer: the gallbladder connects to the bile duct via the cystic duct; verify primary site
- •C25.0 — Head of pancreas: pancreatic head tumors may compress or invade the bile duct; code the primary site