2027 ICD-10-CM Diagnosis Code M60.18Interstitial myositis, other site

ICD-10-CM Codes›M00–M99›M60-M63›M60

ICD-10-CM M60.18
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M60.18 is a billable ICD-10-CM diagnosis code for interstitial myositis, other site. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 557 through 558. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Muscle disorders.

Code Identity

ICD-10-CM Code
M60.18
Billable Status
Yes — Valid for Submission
Code Describes
Interstitial myositis, other site
Short Description
Interstitial myositis, other site
Same as the full description in the CMS dataset.
Parent Code
M60.1
Interstitial myositis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM60-M63Disorders of muscles
CategoryM60Myositis
This CodeM60.18Interstitial myositis, other site

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M60.18: its own notes plus those printed at M60, block M60-M63, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block M60-M63 Disorders of muscles applies to 420 codes
  • dermatopolymyositis (M33.-)
  • myopathy in amyloidosis (E85.-)
  • myopathy in polyarteritis nodosa (M30.0)
  • myopathy in rheumatoid arthritis (M05.32)
  • myopathy in scleroderma (M34.-)
  • myopathy in Sjögren's syndrome (M35.03)
  • myopathy in systemic lupus erythematosus (M32.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From M60 Myositis applies to 111 codes
  • inclusion body myositis [IBM] (G72.41)
From Block M60-M63 Disorders of muscles applies to 420 codes
  • muscular dystrophies and myopathies (G71-G72)
From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • arthropathic psoriasis (L40.5-)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • compartment syndrome (traumatic) (T79.A-)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

General instructions on how these codes are used.

From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name M60.18, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming M60.18: they are not reported together with it, unless the two conditions are unrelated.

  • G72 Other and unspecified myopathies
    myositis (M60.-) names M60.-, which includes this code
  • M79.1 Myalgia
    myositis (M60.-) names M60.-, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming M60.18: its condition is not part of those codes, and both may be reported when the patient has both.

  • G71 Primary disorders of muscles
    myositis (M60.-) names M60.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Interstitial Myositis

    a form of myositis that is characterized by the formation of connective tissue within the muscle.

  • Myositis

    inflammation of a muscle or muscle tissue.

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 M60.18 to ICD-9-CMHistory

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

ICD-9-CM
728.81 Interstitial myositis
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About M60.18Overview

What is the ICD-10 code for interstitial myositis, other site?

The ICD-10-CM code for interstitial myositis, other site is M60.18 (sometimes written as M6018). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M60.18 (Interstitial myositis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report interstitial myositis, other site on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M60.18 group to?

When interstitial myositis, other site is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8873 to 1.4883 depending on complications. Higher weights mean higher Medicare reimbursement.

Can M60.18 be reported with a code from M33?

Not as a rule. The Excludes1 note at block M60-M63, which applies to M60.18, lists "dermatopolymyositis (M33.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of M60.18?

Under the General Equivalence Mappings, interstitial myositis, other site converts to ICD-9-CM 728.81 (interstitial myositis). The mapping is approximate, so confirm the match fits the documentation.