2026 ICD-10-CM Diagnosis Code M12.212Villonodular synovitis (pigmented), left shoulder

ICD-10-CM Codes›M00–M99›M05-M14›M12

ICD-10-CM M12.212
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M12.212 is a billable ICD-10-CM diagnosis code for villonodular synovitis (pigmented), left shoulder. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M12.212
Billable Status
Yes — Valid for Submission
Code Describes
Villonodular synovitis (pigmented), left shoulder
Short Description
Villonodular synovitis (pigmented), left shoulder
Same as the full description in the CMS dataset.
Parent Code
M12.21
Villonodular synovitis (pigmented), shoulder

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM12Other and unspecified arthropathy
This CodeM12.212Villonodular synovitis (pigmented), left shoulder

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Diffuse tenosynovial giant cell tumor of bilateral glenohumeral joints
  • Diffuse tenosynovial giant cell tumor of glenohumeral joint
  • Diffuse tenosynovial giant cell tumor of left glenohumeral joint
  • Diffuse tenosynovial giant cell tumor of right glenohumeral joint
  • Diffuse tenosynovial giant cell tumor of shoulder region
  • Mass of joint of bilateral shoulder regions
  • Mass of joint of left shoulder
  • Mass of joint of left shoulder region
  • Mass of joint of right shoulder
  • Mass of joint of right shoulder region

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

Joint Disorders

Your joints are places where two or more bones come together. Your shoulders, elbows, hips, knees, and knuckles are all joints. Your spine has joints, too.

The full article covers:

  • What are joints?
  • What are joint disorders?
  • What diseases can affect the joints?
  • What types of joint disorders happen from sudden injuries?
  • What types of joint disorders happen from overuse?
  • How can I keep my joints healthy?

Read the full article at MedlinePlus

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

Convert M12.212 to ICD-9-CMHistory

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

ICD-9-CM
719.21 Villonod synovit-shlder
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 M12.212Overview

Is M12.212 (Villonodular synovitis (pigmented), shoulder) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report villonodular synovitis (pigmented), left shoulder on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M12.212 group to?

When villonodular synovitis (pigmented), left shoulder is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M12.212?

Under the General Equivalence Mappings, villonodular synovitis (pigmented), left shoulder converts to ICD-9-CM 719.21 (villonod synovit-shlder). 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.