What is ICD-10 code C70.9?

C70.9 is the ICD-10-CM diagnosis code for Malignant neoplasm of meninges, unspecified. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C70.9 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C70.9 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C70.9 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C70.9 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C70.9 map to under V28?

C70.9 maps to CMS-HCC V28 20 (Lung and Other Severe Cancers). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does C70.9 pay in RAF?

C70.9 carries a community, non-dual, aged (CNA) RAF weight of 1.136 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for C70.9?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C70.9, V28 maps to Lung and Other Severe Cancers at RAF 1.136 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports C70.9?

Use this code only when the specific site of the meningeal malignancy cannot be determined; if the location is documented (cerebral, spinal, or other specific site), use the more specific C70.0-C70.8 codes instead Ensure documentation includes staging information and any treatment plans, as meningeal cancers typically require coordination with oncology and may involve chemotherapy, radiation, or surgery Because C70.9 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM C70.9: Malignant neoplasm

C70.9 maps to CMS-HCC V28 20 (RAF 1.136). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC Buddy coding tools

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Code lookupC70.9Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C70.9

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

Malignant neoplasm of meninges, unspecified

This code represents cancer that has developed in the meninges, which are the protective membranes surrounding the brain and spinal cord, but the specific location of the cancer within these membranes has not been specified. This is a serious condition requiring immediate medical attention and treatment.

Buddy Insight

This unspecified meningeal malignancy code indicates a confirmed malignant tumor of the meninges where the specific location (cerebral versus spinal) has not been documented.

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

RAF 1.136

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Mapped

HCC 9

HHS-HCC 9

Varies by metal level

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.111

RXHCC

Mapped

HCC 22

Cancer, Other Specified Sites

RAF 0.124

Code Book Path

Official

C70Malignant neoplasm of meninges

C70.9Malignant neoplasm of meninges, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C70.9 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C70.9 in this effective period.

Related Child Codes

Official

C70.0Malignant neoplasm of cerebral meninges

C70.1Malignant neoplasm of spinal meninges

Includes

Official

ICD-10-CM does not list Includes notes for C70.9 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C70.9 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C70.9 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C70.9 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C70.9 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology confirming malignancy of the meninges

Evidence that specific location (cerebral versus spinal) was sought but could not be determined

Imaging reports that should be reviewed for location details

Provider query documenting attempts to obtain specificity

MEAT Support

HCC Buddy guidance

Pathology confirming malignancy of the meninges

Evidence that specific location (cerebral versus spinal) was sought but could not be determined

Imaging reports that should be reviewed for location details

Provider query documenting attempts to obtain specificity

Audit Caution

HCC Buddy guidance

Defaulting to unspecified when imaging clearly shows cerebral or spinal location

Not querying the provider when MRI or CT clearly identifies the meningeal level

Coding meningeal carcinomatosis (a metastatic process) as primary meningeal malignancy

Common Mistakes

HCC Buddy guidance

C70.0 — Cerebral meninges: use when brain meninges are documented

C70.1 — Spinal meninges: use when spinal meninges are documented

D32.9 — Benign neoplasm of meninges, unspecified: only use C70.9 for confirmed malignant tumors

C79.32/C79.49 — Secondary meningeal neoplasm: distinguish primary from metastatic disease

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 C70.9 an HCC code?

Yes. C70.9 (Malignant neoplasm of meninges, unspecified) maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24), with a community non-dual aged RAF of 1.136. It is billable for payment year 2026.

Coder answer: C70.9 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: C70.9
Description: Malignant neoplasm of meninges, unspecified
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.111

RxHCCHCC 22, Cancer, Other Specified Sites

0.124

Each model's RAF is its CMS base weight for that model's standard population, so 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 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.

Work C70.9 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C70.9

For C70.9 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 C70.9 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C70.9 is the ICD-10-CM diagnosis code for malignant neoplasm of meninges, unspecified. This code represents cancer that has developed in the meninges, which are the protective membranes surrounding the brain and spinal cord, but the specific location of the cancer within these membranes has not been specified. This is a serious condition requiring immediate medical attention and treatment. C70.9 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, C70.9 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 1.136. Under the older CMS-HCC V24 model, C70.9 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. 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 the specific site of the meningeal malignancy cannot be determined; if the location is documented (cerebral, spinal, or other specific site), use the more specific C70.0-C70.8 codes instead. Because C70.9 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 C70.9 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 site of the meningeal malignancy cannot be determined; if the location is documented (cerebral, spinal, or other specific site), use the more specific C70.0-C70.8 codes instead
•Ensure documentation includes staging information and any treatment plans, as meningeal cancers typically require coordination with oncology and may involve chemotherapy, radiation, or surgery

Clinical Significance

This unspecified meningeal malignancy code indicates a confirmed malignant tumor of the meninges where the specific location (cerebral versus spinal) has not been documented. While it still captures the high-acuity cancer diagnosis for risk adjustment, it represents a documentation gap that can be addressed through review of imaging and surgical records.

Documentation Requirements

✓Pathology confirming malignancy of the meninges
✓Evidence that specific location (cerebral versus spinal) was sought but could not be determined
✓Imaging reports that should be reviewed for location details
✓Provider query documenting attempts to obtain specificity
✓Current treatment status and clinical stage

Commonly Confused Codes

•C70.0: Cerebral meninges: use when brain meninges are documented
•C70.1: Spinal meninges: use when spinal meninges are documented
•D32.9: Benign neoplasm of meninges, unspecified: only use C70.9 for confirmed malignant tumors
•C79.32/C79.49: Secondary meningeal neoplasm: distinguish primary from metastatic disease