C64.9
BillableMalignant neoplasm of unspecified kidney, except renal pelvis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C64.9 an HCC code?
Yes. C64.9 maps to Bladder, Colorectal, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Colorectal, Bladder, 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 C64.9
For C64.9to 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 C64.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C64.9 is the ICD-10-CM diagnosis code for malignant neoplasm of unspecified kidney, except renal pelvis. Cancer of the kidney when the side (left or right) is not specified or documented. C64.9 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of urinary tract (c64-c68).
Under the CMS-HCC V28 risk adjustment model, C64.9 maps to Bladder, Colorectal, and Other Cancers (HCC 22) with a community, non-dual, aged base RAF weight of 0.363. Under the older CMS-HCC V24 model, C64.9 maps to Colorectal, Bladder, and Other Cancers (HCC 11) with a community, non-dual, aged base RAF weight of 0.307. 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.
Query the provider or imaging reports to determine laterality before assigning this code. Because C64.9 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 C64.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Query the provider or imaging reports to determine laterality before assigning this code
- •Use only when laterality cannot be determined despite thorough documentation review
Clinical Significance
Unspecified kidney cancer should only be used when laterality truly cannot be determined. In modern clinical practice with routine cross-sectional imaging, laterality is almost always determinable. This code is a frequent audit target because laterality information is typically available in imaging or surgical reports even when not stated in the clinical note.
Documentation Requirements
- ✓Confirmation of kidney malignancy
- ✓Evidence of query attempt for laterality
- ✓Pathology or imaging results
- ✓Treatment status and plan