C70.9
BillableMalignant neoplasm of meninges, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C70.9 an HCC code?
Yes. C70.9 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers 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 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.
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 0.000. 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