M85.579
BillableAneurysmal bone cyst, unspecified ankle and foot
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M85.579 an HCC code?
No. M85.579 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
M85.579 is the ICD-10-CM diagnosis code for aneurysmal bone cyst, unspecified ankle and foot. A fluid-filled cavity in the bone of the ankle or foot with unspecified side that can cause swelling and weakening of the bone structure. M85.579 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering disorders of bone density and structure (m80-m85).
M85.579 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Use only when laterality cannot be determined; attempt to obtain clarification from the provider.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M85.579 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use only when laterality cannot be determined; attempt to obtain clarification from the provider
- •This unspecified code is less preferred; use specific right or left codes when documentation permits