2026 ICD-10-CM Diagnosis Code M60.831Other myositis, right forearm

ICD-10-CM Codes›M00–M99›M60-M63›M60

ICD-10-CM M60.831
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M60.831 is a billable ICD-10-CM diagnosis code for other myositis, right forearm. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 555 through 556. Coders also document this condition as bilateral myositis of forearms. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Muscle disorders.

Code Identity

ICD-10-CM Code
M60.831
Billable Status
Yes — Valid for Submission
Code Describes
Other myositis, right forearm
Short Description
Other myositis, right forearm
Same as the full description in the CMS dataset.
Parent Code
M60.83
Other myositis, forearm

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM60-M63Disorders of muscles
CategoryM60Myositis
This CodeM60.831Other myositis, right forearm

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral myositis of forearms
  • Myositis of left forearm
  • Myositis of right forearm

Clinical ClassificationClinical

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

CCSR MUS026
Muscle disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Myositis

Myositis means inflammation of the muscles that you use to move your body. An injury, infection, or autoimmune disease can cause it. Two specific kinds are polymyositis and dermatomyositis. Polymyositis causes muscle weakness, usually in the muscles closest to the trunk of your body.

Read the full article at MedlinePlus

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

Convert M60.831 to ICD-9-CMHistory

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

ICD-9-CM
729.1 Myalgia and myositis NOS
Approximate The match is approximate rather than exact.

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 M60.831Overview

Is M60.831 (Other myositis, forearm) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other myositis, right forearm on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M60.831 group to?

When other myositis, right forearm is the principal diagnosis on an inpatient stay, it groups to MS-DRG 555, 556, with relative weights from 0.8306 to 1.3218 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M60.831?

Under the General Equivalence Mappings, other myositis, right forearm converts to ICD-9-CM 729.1 (myalgia and myositis NOS). The mapping is approximate, so confirm the match fits the documentation.

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.