C65.1
BillableMalignant neoplasm of right renal pelvis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C65.1 an HCC code?
Yes. C65.1 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 C65.1
For C65.1to 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 C65.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C65.1 is the ICD-10-CM diagnosis code for malignant neoplasm of right renal pelvis. Cancer that starts in the right renal pelvis, the funnel-shaped structure inside the kidney that collects and drains urine. C65.1 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, C65.1 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, C65.1 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.
Distinguish this from C64.1 by confirming the tumor originates in the renal pelvis, not the kidney parenchyma. Because C65.1 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 C65.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish this from C64.1 by confirming the tumor originates in the renal pelvis, not the kidney parenchyma
- •Verify laterality documentation specifies 'right' kidney
Clinical Significance
Right renal pelvis cancer is a urothelial (transitional cell) carcinoma arising from the renal pelvis lining — the funnel-shaped urine collecting structure inside the kidney. This is classified as an upper tract urothelial carcinoma and has a different biology and treatment approach than renal cell carcinoma of the kidney parenchyma. Distinguishing renal pelvis from kidney parenchyma cancer is a critical coding distinction.
Documentation Requirements
- ✓Pathology confirming malignancy originating in the right renal pelvis
- ✓Histologic type (transitional cell/urothelial carcinoma in most cases)
- ✓Grade and staging
- ✓Imaging confirming the tumor is in the renal pelvis, not the kidney cortex
- ✓Urine cytology results if performed
- ✓Treatment plan (nephroureterectomy is the standard approach)
Commonly Confused Codes
- •C64.1 — Right kidney cancer; the kidney parenchyma and renal pelvis are different anatomical sites with different histologies
- •C65.2 — Left renal pelvis; verify laterality
- •C65.9 — Unspecified renal pelvis; use C65.1 when right is documented
- •C66.1 — Right ureter cancer; renal pelvis and ureter are contiguous but coded separately