C23
BillableMalignant neoplasm of gallbladder
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C23 an HCC code?
Yes. C23 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 C23
For C23 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 C23 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C23 is the ICD-10-CM diagnosis code for malignant neoplasm of gallbladder. A cancer that develops in the gallbladder, the small organ that stores bile. It is often diagnosed at an advanced stage because early symptoms are uncommon. C23 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, C23 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, C23 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 any history of gallstones, primary sclerosing cholangitis, or other risk factors. Because C23 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 C23 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Gallbladder cancer is an aggressive malignancy that is often discovered incidentally during cholecystectomy for presumed benign disease. It is the most common biliary tract malignancy and has a poor prognosis when diagnosed at advanced stages because symptoms typically occur late. The anatomical location adjacent to the liver, bile ducts, and major vessels makes surgical management complex, often requiring radical cholecystectomy with liver wedge resection and lymph node dissection.
Documentation Requirements
- ✓Pathological confirmation of malignancy (especially in incidental findings during cholecystectomy)
- ✓Histological type (adenocarcinoma is most common; also squamous cell, neuroendocrine)
- ✓T-stage: depth of gallbladder wall invasion is critical for management decisions
- ✓Any history of gallstones, porcelain gallbladder, or primary sclerosing cholangitis
- ✓Whether the diagnosis was incidental at surgery or clinically suspected
Commonly Confused Codes
- •K82.8 — Other specified diseases of gallbladder: benign gallbladder conditions; ensure malignancy is confirmed
- •C24.0 — Extrahepatic bile duct cancer: gallbladder cancer may involve the cystic duct or common bile duct; code the primary site
- •C22.1 — Intrahepatic bile duct carcinoma: intrahepatic location, not gallbladder
- •D13.5 — Benign neoplasm of extrahepatic bile ducts: benign, not malignant; includes gallbladder polyps that are benign