C50.911
BillableMalignant neoplasm of unspecified site of right female breast
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C50.911 an HCC code?
Yes. C50.911 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 C50.911
For C50.911 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 C50.911 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C50.911 is the ICD-10-CM diagnosis code for malignant neoplasm of unspecified site of right female breast. Breast cancer in a female patient affecting the right breast, but the specific location within the breast is not identified or documented. C50.911 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, C50.911 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, C50.911 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.
This code is used when a female patient has breast cancer but the exact site (upper outer, nipple, etc.) is not specified. Because C50.911 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 C50.911 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is used when a female patient has breast cancer but the exact site (upper outer, nipple, etc.) is not specified
- •Review pathology and imaging reports to determine if a more specific site code can be assigned
Clinical Significance
Malignant neoplasm of unspecified site of right female breast is commonly used when a breast cancer diagnosis is confirmed with laterality but the specific quadrant or subsite is not documented. While better than a fully unspecified code, coders should attempt to identify the specific breast location from pathology, imaging, or operative reports before accepting this designation.
Documentation Requirements
- ✓Confirmed female patient sex
- ✓Laterality documented as right breast
- ✓Confirmation that a more specific site cannot be determined from available documentation
- ✓Histological type and grade
- ✓TNM staging
- ✓Receptor status (estrogen receptor, progesterone receptor, HER2)
- ✓Current treatment phase (active treatment, surveillance, or history)
Commonly Confused Codes
- •C50.411 — Upper-outer quadrant of right female breast; use when the specific quadrant is documented
- •C50.811 — Overlapping sites of right female breast; use when tumor spans multiple specific sites
- •C50.912 — Unspecified site of left female breast; laterality confusion
- •C50.919 — Unspecified site of unspecified female breast; use only when laterality is also unknown
- •Z85.3 — Personal history of malignant neoplasm of breast; use only when cancer is no longer present