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ICD-10-CM 2027 diagnosis code

M60.121Interstitial myositis, right upper arm

✓ Billable / specific

M60.121 is a valid, billable ICD-10-CM code for interstitial myositis, right upper arm. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M60.121

M60.121 is the ICD-10-CM diagnosis code for interstitial myositis, right upper arm. It belongs to category M60 (myositis), block M60-M63 (disorders of muscles) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M60.12 (interstitial myositis, upper arm), M60.121 is specifically for interstitial myositis, right upper arm. Related codes cover left upper arm (M60.122) and unspecified upper arm (M60.129).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 557 (Tendonitis, Myositis and Bursitis with MCC, relative weight 1.489) and DRG 558 (Tendonitis, Myositis and Bursitis without MCC, relative weight 0.8875), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 728.81 (interstitial myositis).

Notes that apply from higher levels

Instructions written at a parent level also apply to M60.121.

› From M60 Myositis
Excludes2
  • inclusion body myositis [IBM] (G72.41)

Broader instructions also apply from M60-M63 Disorders of muscles and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 08 · Diseases and Disorders of the Musculoskeletal System and Connective Tissue

ICD-9-CM equivalent

Converter →
  • 728.81Interstitial myositisapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about M60.121

Is M60.121 billable?

Yes. M60.121 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M60.121 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M60.121 as a principal diagnosis.

Is M60.121 a CC or MCC?

No. M60.121 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does M60.121 group to?

M60.121 is used in the MS-DRG v44.0 logic for MS-DRG 557 (Tendonitis, Myositis and Bursitis with MCC) and MS-DRG 558 (Tendonitis, Myositis and Bursitis without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for M60.121?

The CMS General Equivalence Mappings map M60.121 to ICD-9-CM 728.81.