C79.10
BillableSecondary malignant neoplasm of unspecified urinary organs
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C79.10 an HCC code?
Yes. C79.10 maps to Metastatic Cancer to Peritoneum and Other Specified Sites under the CMS-HCC V28 risk adjustment model (and Metastatic Cancer and Acute Leukemia 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 C79.10
For C79.10 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 C79.10 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C79.10 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of unspecified urinary organs. Cancer that has spread to the urinary system (kidneys, ureters, bladder, or urethra) but the specific organ location is not specified. C79.10 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of ill-defined, other secondary and unspecified sites (c76-c80).
Under the CMS-HCC V28 risk adjustment model, C79.10 maps to Metastatic Cancer to Peritoneum and Other Specified Sites (HCC 18) with a community, non-dual, aged base RAF weight of 0.368. Under the older CMS-HCC V24 model, C79.10 maps to Metastatic Cancer and Acute Leukemia (HCC 8) with a community, non-dual, aged base RAF weight of 2.484. 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 urinary organ site cannot be determined; if location is known, use more specific codes (C79.01-C79.02 for kidney, C79.11 for bladder). Because C79.10 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 C79.10 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Secondary malignant neoplasm of unspecified urinary organs indicates metastatic cancer has spread to the urinary system but the specific organ (kidney, bladder, ureter, urethra) is not identified. This code reflects incomplete documentation and should trigger a provider query to identify the specific urinary organ involved for more precise coding.
Documentation Requirements
- ✓Primary cancer site documented and coded separately
- ✓Best available description of which urinary organ is involved
- ✓Provider query documenting attempt to clarify the specific urinary organ
- ✓Imaging or cystoscopic findings that may localize the metastatic site
- ✓Urinary symptoms — hematuria, obstruction, frequency changes
Commonly Confused Codes
- •C79.00-C79.02 — Secondary malignant neoplasm of kidney; use kidney-specific codes when kidney is the documented site
- •C79.11 — Secondary malignant neoplasm of bladder; use when bladder is specifically involved
- •C79.19 — Secondary malignant neoplasm of other urinary organs; use when a specific non-kidney, non-bladder urinary organ is identified
- •C68.0-C68.9 — Primary malignant neoplasm of other urinary organs; distinguish primary from secondary