M65.4
BillableRadial styloid tenosynovitis [de Quervain]
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M65.4 an HCC code?
No. M65.4 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
M65.4 is the ICD-10-CM diagnosis code for radial styloid tenosynovitis [de quervain]. Inflammation of the tendon sheath on the thumb side of the wrist, causing pain and swelling, also known as de Quervain's tenosynovitis. M65.4 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering disorders of synovium and tendon (m65-m67).
M65.4 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 code does not require laterality specification; if side-specific, use appropriate fifth character.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M65.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code does not require laterality specification; if side-specific, use appropriate fifth character
- •Document whether condition is related to repetitive activities or trauma for clinical context