C50.521
BillableMalignant neoplasm of lower-outer quadrant of right male breast
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C50.521 an HCC code?
Yes. C50.521 maps to Melanoma and Other Skin Cancers under the CMS-HCC V28 risk adjustment model (and Breast, Prostate, and Other Cancers and Tumors 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 C50.521
For C50.521 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 C50.521 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C50.521 is the ICD-10-CM diagnosis code for malignant neoplasm of lower-outer quadrant of right male breast. Cancer that develops in the lower-outer area of the right breast in men. C50.521 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of breast (c50).
Under the CMS-HCC V28 risk adjustment model, C50.521 maps to Melanoma and Other Skin Cancers (HCC 23) with a community, non-dual, aged base RAF weight of 0.251. Under the older CMS-HCC V24 model, C50.521 maps to Breast, Prostate, and Other Cancers and Tumors (HCC 12) with a community, non-dual, aged base RAF weight of 0.150. 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.
Confirm male gender and right breast with lower-outer quadrant location. Because C50.521 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 C50.521 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm male gender and right breast with lower-outer quadrant location
- •Male breast cancer codes use different digit patterns than female codes; verify correct code selection
Clinical Significance
Male breast cancer of the lower-outer quadrant of the right breast is exceedingly rare, as male breast cancer itself accounts for less than 1% of all breast cancers. Due to the smaller amount of breast tissue in males, tumors are often closer to the nipple-areolar complex, making accurate quadrant documentation essential for surgical planning.
Documentation Requirements
- ✓Confirmed male patient sex
- ✓Laterality documented as right breast
- ✓Specific quadrant identified as lower-outer
- ✓Histological type (invasive ductal carcinoma predominates in males)
- ✓BRCA genetic testing status if applicable
- ✓TNM staging and receptor status
- ✓Family history of breast cancer if documented