M61.121
BillableMyositis ossificans progressiva, right upper arm
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M61.121 an HCC code?
No. M61.121 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
M61.121 is the ICD-10-CM diagnosis code for myositis ossificans progressiva, right upper arm. A rare genetic condition where muscle tissue in the right upper arm gradually turns into bone, causing progressive stiffness and loss of movement. M61.121 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering disorders of muscles (m60-m63).
M61.121 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.
This is a laterality-specific code; ensure documentation clearly indicates right side involvement.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M61.121 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a laterality-specific code; ensure documentation clearly indicates right side involvement
- •Myositis ossificans progressiva (MOP) is a rare genetic disorder - verify diagnosis is confirmed and not confused with other ossification conditions