M85.539
BillableAneurysmal bone cyst, unspecified forearm
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M85.539 an HCC code?
No. M85.539 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
M85.539 is the ICD-10-CM diagnosis code for aneurysmal bone cyst, unspecified forearm. A benign bone cyst filled with blood in the forearm when the specific side is not documented or specified. M85.539 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).
M85.539 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 from available documentation.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M85.539 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 from available documentation
- •Query provider or review imaging to determine if right or left forearm is affected