2026 ICD-10-CM Diagnosis Code M65.4Radial styloid tenosynovitis [de Quervain]

ICD-10-CM Codes›M00–M99›M65-M67›M65

ICD-10-CM M65.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M65.4 is a billable ICD-10-CM diagnosis code for radial styloid tenosynovitis [de Quervain]. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 557 through 558. Coders also document this condition as bilateral tenosynovitis of radial styloids. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M65.4
Billable Status
Yes — Valid for Submission
Code Describes
Radial styloid tenosynovitis [de Quervain]
Short Description
Radial styloid tenosynovitis [de Quervain]
Same as the full description in the CMS dataset.
Parent Code
M65
Synovitis and tenosynovitis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM65Synovitis and tenosynovitis
This CodeM65.4Radial styloid tenosynovitis [de Quervain]

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral tenosynovitis of radial styloids
  • Radial styloid tenosynovitis
  • Tenosynovitis of left radial styloid
  • Tenosynovitis of right radial styloid

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • De Quervain's
      • disease (tendon sheath)
    • Disease, diseased
      • de Quervain's (tendon sheath)
    • Quervain's disease
    • Tenosynovitis
      • radial styloid

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS009
Tendon and synovial disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Hand Injuries and Disorders

No matter how old you are or what you do for a living, you are always using your hands. When there is something wrong with them, you may not be able to do your regular activities.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M65.4 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
727.04 Radial styloid tenosynov
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M65.4Overview

Is M65.4 (Synovitis and tenosynovitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report radial styloid tenosynovitis [de Quervain] on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M65.4 group to?

When radial styloid tenosynovitis [de Quervain] is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8932 to 1.4869 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M65.4?

Under the General Equivalence Mappings, radial styloid tenosynovitis [de Quervain] converts to ICD-9-CM 727.04 (radial styloid tenosynov). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.