C71.5 ICD-10-CM Code: Malignant neoplasm of cerebral ventricle
C71.5 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of eye, brain and other parts of central nervous system (C69-C72)
C71.5
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of cerebral ventricle
A malignant (cancerous) tumor that originates in the cerebral ventricles, which are fluid-filled spaces within the brain. This is a serious brain cancer that requires immediate medical attention and treatment.
Buddy Insight
Cerebral ventricular malignancy includes tumors arising within the fluid-filled cavities of the brain, such as choroid plexus carcinoma, ependymoma, and central neurocytoma.
CMS-HCC V28
MappedHCC 20
Coefficient HCC 20: 1.136 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 009
Code-level coefficient reference
ESRD/PACE
MappedHCC 10
Code-level coefficient reference
RXHCC
MappedHCC 22
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C71.5. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for C71.5. Check the code and parent instructions in the Code Book.
Related Codes
Includes
OfficialNo Includes notes are included in this display for C71.5. Check the code and parent instructions in the Code Book.
Excludes 1
Official- malignant neoplasm of fourth cerebral ventricle (C71.7)
- malignant neoplasm of cranial nerves (C72.2-C72.5)Inherited from C71
- retrobulbar malignant neoplasm (C69.6-)Inherited from C71
Code First
OfficialNo Code First sequencing instructions are included in this display for C71.5. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for C71.5. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for C71.5. 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 C71.5 an HCC code?
Yes. C71.5 (Malignant neoplasm of cerebral ventricle) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. 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: C71.5 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C71.5
- Description
- Malignant neoplasm of cerebral ventricle
- HCC (V28)
- HCC 20 — Lung and Other Severe Cancers
- RAF reference coefficient
- 1.136
- 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 C71.5 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C71.5
For C71.5, 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
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What This Code Means
C71.5 is the ICD-10-CM diagnosis code for malignant neoplasm of cerebral ventricle. A malignant (cancerous) tumor that originates in the cerebral ventricles, which are fluid-filled spaces within the brain. This is a serious brain cancer that requires immediate medical attention and treatment. C71.5 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of eye, brain and other parts of central nervous system (c69-c72).
Under the CMS-HCC V28 risk adjustment model, C71.5 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C71.5; use the applicable model and payment year when reviewing the V28 mapping. 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.
Verify the histological type of the neoplasm from the pathology report, as additional characters may be needed to specify behavior (malignant, in situ, etc.) and laterality if applicable. For C71.5, 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 C71.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the histological type of the neoplasm from the pathology report, as additional characters may be needed to specify behavior (malignant, in situ, etc.) and laterality if applicable
- •Ensure this code is used only for primary malignant tumors of the cerebral ventricles; use different codes for metastatic cancers to the ventricles or benign tumors
Clinical Significance
Cerebral ventricular malignancy includes tumors arising within the fluid-filled cavities of the brain, such as choroid plexus carcinoma, ependymoma, and central neurocytoma. These tumors can obstruct cerebrospinal fluid flow causing hydrocephalus, and may require emergent intervention for raised intracranial pressure in addition to definitive cancer treatment.
Documentation Requirements
- ✓Pathology confirming malignancy with specific histological type (choroid plexus carcinoma, ependymoma, subependymoma)
- ✓MRI brain documenting the specific ventricle involved (lateral, third, fourth)
- ✓Assessment for hydrocephalus and intracranial pressure
- ✓Cerebrospinal fluid analysis if obtained
- ✓Distinction from benign ventricular tumors
Excludes 1, Do NOT code together
- malignant neoplasm of fourth cerebral ventricle (C71.7)
Commonly Confused Codes
- •C71.0: Cerebrum except lobes and ventricles: C71.0 explicitly excludes ventricles: use C71.5 for ventricular tumors
- •C71.6: Cerebellum: fourth ventricle tumors are at the cerebellum border; verify if the tumor is intraventricular or cerebellar
- •D33.0: Benign neoplasm of brain: benign ventricular tumors should not use C71.5
- •C71.7: Brain stem: fourth ventricle floor tumors may extend into the brain stem