C7B.04 ICD-10-CM Code: Secondary carcinoid tumors of peritoneum
C7B.04 maps to CMS-HCC V28 17. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Neoplasms (C00-D49) / Secondary neuroendocrine tumors (C7B)
C7B.04
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSecondary 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.
Buddy Insight
Secondary carcinoid tumors of the peritoneum indicates carcinoid cancer that has spread to the peritoneal lining of the abdominal cavity.
CMS-HCC V28
MappedHCC 17
Coefficient HCC 17: 4.209 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 008
Code-level coefficient reference
ESRD/PACE
MappedHCC 8
Code-level coefficient reference
RXHCC
MappedHCC 20
Code-level coefficient reference
Code Book Path
Inclusion Terms
Official- Mesentery metastasis of carcinoid tumor
Excludes 2
OfficialNo Excludes 2 notes are included in this display for C7B.04. Check the code and parent instructions in the Code Book.
Related Codes
Includes
OfficialNo Includes notes are included in this display for C7B.04. Check the code and parent instructions in the Code Book.
Excludes 1
OfficialNo Excludes 1 notes are included in this display for C7B.04. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for C7B.04. Check the code and parent instructions in the Code Book.
Use Additional
Official- code to identify any functional activityInherited from C7B
Code Also
OfficialNo Code Also instructions are included in this display for C7B.04. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is C7B.04 an HCC code?
Yes. C7B.04 (Secondary carcinoid tumors of peritoneum) maps to HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 4.209. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: C7B.04 is billable and maps to V28 HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C7B.04
- Description
- Secondary carcinoid tumors of peritoneum
- HCC (V28)
- HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
- RAF reference coefficient
- 4.209
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work C7B.04 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C7B.04
For C7B.04, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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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 Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic (HCC 17) with a source-labeled community, non-dual, aged reference coefficient of 4.209. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Use this code only when carcinoid tumor has metastasized to the peritoneum; document the primary site separately. For C7B.04, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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