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C71.0 ICD-10-CM Code: Malignant neoplasm of cerebrum, except lobes and ventricles

C71.0 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 coding software

ICD-10-CM Code View

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Code lookupC71.0

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of eye, brain and other parts of central nervous system (C69-C72)

C71.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of cerebrum, except lobes and ventricles

Cancer of the main part of the brain (cerebrum) excluding specific lobes and ventricles. This code is used when the tumor location is not more specifically identified.

Buddy the Bee presenting code insight

Buddy Insight

Malignant neoplasm of the cerebrum (excluding specific lobes and ventricles) represents a primary brain cancer in the largest part of the brain when the specific lobe cannot be determined.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 20

Coefficient HCC 20: 1.136 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 009

Code-level coefficient reference

ESRD/PACE

HCC 10

Code-level coefficient reference

RXHCC

HCC 22

Code-level coefficient reference

Code Book Path

Official
C71Malignant neoplasm of brainC71.0Malignant neoplasm of cerebrum, except lobes and ventricles

Inclusion Terms

Official
  • Malignant neoplasm of supratentorial NOS

Excludes 2

Official

No Excludes 2 notes are included in this display for C71.0. Check the code and parent instructions in the Code Book.

Related Codes

Official
C71.1Malignant neoplasm of frontal lobeC71.2Malignant neoplasm of temporal lobeC71.3Malignant neoplasm of parietal lobeC71.4Malignant neoplasm of occipital lobeC71.5Malignant neoplasm of cerebral ventricle

Includes

Official

No Includes notes are included in this display for C71.0. Check the code and parent instructions in the Code Book.

Excludes 1

Official
  • malignant neoplasm of cranial nerves (C72.2-C72.5)Inherited from C71
  • retrobulbar malignant neoplasm (C69.6-)Inherited from C71

Code First

Official

No Code First sequencing instructions are included in this display for C71.0. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C71.0. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C71.0. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Pathology confirming primary malignancy with histological type and World Health Organization grade (glioblastoma, astrocytoma, oligodendroglioma)
MRI brain documenting tumor location within the cerebrum
Documentation that a specific lobe could not be identified (tumor may span deep structures)
Molecular markers if available (IDH mutation, MGMT methylation, 1p/19q codeletion)

MEAT Support

HCC Buddy guidance
Pathology confirming primary malignancy with histological type and World Health Organization grade (glioblastoma, astrocytoma, oligodendroglioma)
MRI brain documenting tumor location within the cerebrum
Documentation that a specific lobe could not be identified (tumor may span deep structures)
Molecular markers if available (IDH mutation, MGMT methylation, 1p/19q codeletion)

Audit Caution

HCC Buddy guidance
Using C71.0 when imaging or operative report identifies a specific lobe (C71.1-C71.4)
Coding brain metastases from lung, breast, or other cancers as primary brain cancer — use C79.31
Not reviewing neurosurgery or radiology reports that typically specify the lobe or region involved
Confusing World Health Organization grading (tumor aggressiveness) with ICD-10 code selection

Common Mistakes

HCC Buddy guidance
C71.1-C71.4 — Specific cerebral lobe codes: if a lobe is identified (frontal, temporal, parietal, occipital), use the specific code
C71.5 — Cerebral ventricle: ventricular tumors have their own code, not included in C71.0
C71.8 — Overlapping sites: use when tumor clearly spans multiple brain regions
C79.31 — Secondary malignant neoplasm of brain: do not code brain metastases as primary brain cancer

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 C71.0 an HCC code?

Yes. C71.0 (Malignant neoplasm of cerebrum, except lobes and ventricles) 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: C71.0 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
C71.0
Description
Malignant neoplasm of cerebrum, except lobes and ventricles
HCC (V28)
HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient
1.136
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers
1.136
ESRDHCC 10, Lymphoma and Other Cancers
Not separately weighted
RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors
Not separately weighted

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 C71.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C71.0

For C71.0, 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

C71.0 is the ICD-10-CM diagnosis code for malignant neoplasm of cerebrum, except lobes and ventricles. Cancer of the main part of the brain (cerebrum) excluding specific lobes and ventricles. This code is used when the tumor location is not more specifically identified. C71.0 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, C71.0 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 C71.0; 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.

Use this code only when the specific lobe cannot be determined; if lobe is documented, use more specific codes C71.1-C71.4. For C71.0, 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 C71.0 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 the specific lobe cannot be determined; if lobe is documented, use more specific codes C71.1-C71.4
  • •Document the laterality (left or right hemisphere) when available for better clinical specificity

Clinical Significance

Malignant neoplasm of the cerebrum (excluding specific lobes and ventricles) represents a primary brain cancer in the largest part of the brain when the specific lobe cannot be determined. Primary brain cancers including glioblastoma are among the most devastating malignancies, with aggressive treatment requirements and substantial impact on patient function and survival.

Documentation Requirements

  • ✓Pathology confirming primary malignancy with histological type and World Health Organization grade (glioblastoma, astrocytoma, oligodendroglioma)
  • ✓MRI brain documenting tumor location within the cerebrum
  • ✓Documentation that a specific lobe could not be identified (tumor may span deep structures)
  • ✓Molecular markers if available (IDH mutation, MGMT methylation, 1p/19q codeletion)
  • ✓Current treatment status (active treatment, post-surgical, palliative)

Commonly Confused Codes

  • •C71.1-C71.4: Specific cerebral lobe codes: if a lobe is identified (frontal, temporal, parietal, occipital), use the specific code
  • •C71.5: Cerebral ventricle: ventricular tumors have their own code, not included in C71.0
  • •C71.8: Overlapping sites: use when tumor clearly spans multiple brain regions
  • •C79.31: Secondary malignant neoplasm of brain: do not code brain metastases as primary brain cancer

Child Codes

C71.0Malignant neoplasm of cerebrum, except lobes and ventricles
HCC 20
C71.1Malignant neoplasm of frontal lobe
HCC 20
C71.2Malignant neoplasm of temporal lobe
HCC 20
C71.3Malignant neoplasm of parietal lobe
HCC 20
C71.4Malignant neoplasm of occipital lobe
HCC 20
C71.5Malignant neoplasm of cerebral ventricle
HCC 20
C71.6Malignant neoplasm of cerebellum
HCC 20
C71.7Malignant neoplasm of brain stem
HCC 20
C71.8Malignant neoplasm of overlapping sites of brain
HCC 20
C71.9Malignant neoplasm of brain, unspecified
HCC 20

Code Hierarchy

└C71Malignant neoplasm of brain└C71.0Malignant neoplasm of cerebrum, except lobes and ventricles
└C71.0Malignant neoplasm of cerebrum, except lobes and ventricles

Also searched as

  • C71 0
  • C710

For C71.0, 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.

C71.0 maps to CMS-HCC V28 category 20, Lung and Other Severe Cancers. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for C71.0. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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