C7B.04
BillableSecondary carcinoid tumors of peritoneum
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C7B.04 an HCC code?
Yes. C7B.04 maps to Metastatic Cancer and Acute Leukemia under the CMS-HCC V28 risk adjustment model (and Metastatic Cancer and Acute Leukemia 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 C7B.04
For C7B.04 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 C7B.04 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C7B.04 is the ICD-10-CM diagnosis code for secondary carcinoid tumors of peritoneum. Cancer that has spread to the peritoneum (the lining of the abdominal cavity) and originates from neuroendocrine cells that produce carcinoid tumors. C7B.04 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering secondary neuroendocrine tumors (c7b).
Under the CMS-HCC V28 risk adjustment model, C7B.04 maps to Metastatic Cancer and Acute Leukemia (HCC 17) with a community, non-dual, aged base RAF weight of 0.368. Under the older V24 model, C7B.04 mapped to the same category but with a base RAF weight of 2.484 — 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 only when carcinoid tumor has metastasized to the peritoneum; document the primary site separately. Because C7B.04 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 C7B.04 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when carcinoid tumor has metastasized to the peritoneum; document the primary site separately
- •Verify documentation confirms secondary/metastatic status rather than primary peritoneal carcinoid
Clinical Significance
Secondary carcinoid tumors of the peritoneum indicates carcinoid cancer that has spread to the peritoneal lining of the abdominal cavity. Peritoneal carcinomatosis from carcinoid tumors can cause ascites, bowel obstruction, and significant morbidity. This finding is most common with midgut carcinoids (ileal) and represents advanced Stage IV disease requiring multimodal treatment including possible cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy.
Documentation Requirements
- ✓Imaging or surgical documentation of peritoneal carcinoid metastases
- ✓Primary carcinoid tumor site documented and coded separately (C7A codes)
- ✓Extent of peritoneal involvement (localized versus diffuse carcinomatosis)
- ✓Presence or absence of ascites
- ✓Presence or absence of bowel obstruction
- ✓Treatment plan (cytoreductive surgery, HIPEC, systemic therapy)
Commonly Confused Codes
- •C78.6 — Secondary malignant neoplasm of retroperitoneum and peritoneum: Use for non-carcinoid cancer metastatic to the peritoneum
- •C7B.00 — Secondary carcinoid tumors, unspecified site: Use C7B.04 when the peritoneum is specifically documented
- •C48.1-C48.2 — Malignant neoplasm of specified/unspecified parts of peritoneum: These are for primary peritoneal malignancies, not metastatic carcinoid