2026 ICD-10-CM Diagnosis Code M33.12Other dermatomyositis with myopathy

ICD-10-CM Codes›M00–M99›M30-M36›M33

ICD-10-CM M33.12
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M33.12 is a billable ICD-10-CM diagnosis code for other dermatomyositis with myopathy. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. Coders also document this condition as calcification of muscle due to adult dermatomyositis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders.

Code Identity

ICD-10-CM Code
M33.12
Billable Status
Yes — Valid for Submission
Code Describes
Other dermatomyositis with myopathy
Short Description
Other dermatomyositis with myopathy
Same as the full description in the CMS dataset.
Parent Code
M33.1
Other dermatomyositis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM30-M36Systemic connective tissue disorders
CategoryM33Dermatopolymyositis
This CodeM33.12Other dermatomyositis with myopathy

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Calcification of muscle due to adult dermatomyositis
  • Calcinosis due to adult type dermatomyositis

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.

    • Dermatomucosomyositis
      • with
        • myopathy
    • Dermatomyositis(acute) (chronic)
      • specified NEC
        • with
          • myopathy
    • Dermatopolymyositis
      • specified NEC
        • myopathy
    • Poikilodermatomyositis
      • with
        • myopathy

Clinical ClassificationClinical

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

CCSR MUS024
Systemic lupus erythematosus and connective tissue disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Dermatomyositis

    a subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. the illness occurs with approximately equal frequency in children and adults. the skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. the disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. the childhood form of this disease tends to evolve into a systemic vasculitis. dermatomyositis may occur in association with malignant neoplasms. (from adams et al., principles of neurology, 6th ed, pp1405-6)

  • Adult Dermatomyositis

    dermatomyositis in an adult.

  • Childhood Dermatomyositis|JDM|JDM|Juvenile Dermatomyositis|Juvenile Dermatomyositis

    an inflammatory myopathy of childhood resulting in muscle weakness, and associated with a characteristic skin rash.

  • Cutaneous Dermatomyositis Disease Area and Severity Index|CDASI|CDASI

    an instrument that measures activity and damage in the skin of dermatomyositis patients.

  • Dermatomyositis

    inflammation of the skin and muscle.

  • Dermatomyositis Skin Severity Index|DSSI|DSSI

    an assessment of disease activity in the skin of patients with dermatomyositis.

  • Interferon-Induced Helicase C Domain-Containing Protein 1|CADM-140 Autoantigen|Clinically Amyopathic Dermatomyositis Autoantigen 140 kDa|EC 3.6.4.13|Helicard|Helicase with 2 CARD Domains|IFIH1|Interferon-Induced With Helicase C Domain Protein 1|MDA-5|Melanoma Differentiation Associated Protein-5|Melanoma Differentiation-Associated Protein 5|Murabutide Down-Regulated Protein|RLR-2|RNA Helicase-DEAD Box Protein 116

    interferon-induced helicase c domain-containing protein 1 (1025 aa, ~117 kda) is encoded by the human ifih1 gene. this protein is involved in the positive regulation of antiviral responses.

  • Juvenile Dermatomyositis Sine Myositis|Juvenile Amyopathic Dermatomyositis|Juvenile Amyopathic Dermatomyositis|Juvenile Dermatomyositis sine Myositis|Juvenile dermatomyositis without myopathy

    a rare form of juvenile dermatomyositis that manifests with characteristic cutaneous findings for at least six months in the absence of any detectable muscle involvement.

  • Juvenile Dermatomyositis with Myopathy|Juvenile dermatomyositis with myopathy

    evidence of juvenile dermatomyositis with myopathy.

  • Juvenile Dermatomyositis with Other Organ Involvement|Juvenile dermatomyositis with other organ involvement

    evidence of juvenile dermatomyositis with other organ involvement.

  • Juvenile Dermatomyositis with Respiratory Involvement|Juvenile dermatomyositis with respiratory involvement

    evidence of juvenile dermatomyositis with respiratory involvement.

  • Juvenile Dermatomyositis, Organ Involvement Unspecified|Juvenile dermatomyositis, organ involvement unspecified

    evidence of juvenile dermatomyositis, organ involvement unspecified.

  • Other Dermatomyositis with Myopathy|Other dermatomyositis with myopathy

    evidence of other dermatomyositis with myopathy not specified elsewhere.

  • Other Dermatomyositis with Other Organ Involvement|Other dermatomyositis with other organ involvement

    evidence of other dermatomyositis with other organ involvement not specified elsewhere.

  • Other Dermatomyositis with Respiratory Involvement|Other dermatomyositis with respiratory involvement

    evidence of other dermatomyositis with respiratory involvement not specified elsewhere.

  • Other Dermatomyositis without Myopathy|Other dermatomyositis without myopathy

    evidence of other dermatomyositis without myopathy not specified elsewhere.

  • Other Dermatomyositis, Organ Involvement Unspecified|Other dermatomyositis, organ involvement unspecified

    evidence of other dermatomyositis, organ involvement unspecified not specified elsewhere.

  • Chromodomain-Helicase-DNA-Binding Protein 3|ATP-Dependent Helicase CHD3|CHD-3|CHD3|Chromodomain Helicase DNA Binding Protein 3|Chromodomain Helicase DNA-Binding Protein 3|Dermatomyositis Autoantigen Mi-2 Alpha|EC 3.6.4.12|MI-2 ALPHA ANTIGEN|MI-2 Alpha|MI-2a|Mi-2 Alpha|Mi-2 Autoantigen 240 kDa Protein|Mi2-Alpha|Zinc Finger Helicase|hZFH

    chromodomain-helicase-dna-binding protein 3 (2000 aa, ~227 kda) is encoded by the human chd3 gene. this protein is involved in chromatin remodeling, spindle organization during mitosis and transcriptional repression.

  • Chromodomain-Helicase-DNA-Binding Protein 4|ATP-Dependent Helicase CHD4|CHD-4|CHD4|Chromodomain Helicase DNA-Binding Protein 4|Dermatomyositis Autoantigen Mi-2 Beta|EC 3.6.4.12|MI-2 BETA ANTIGEN|MI-2 Beta|MI-2b|Mi-2 Autoantigen 218 kDa Protein|Mi-2 Beta|Mi2-Beta

    chromodomain-helicase-dna-binding protein 4 (1912 aa, ~218 kda) is encoded by the human chd4 gene. this protein is involved in chromatin remodeling.

  • MI-2 Antigens|Dermatomyositis Autoantigen Mi-2|MI-2 ANTIGENS|Major Dermatomyositis-specific Mi-2 Autoantigen

    antigens derived from certain helicases in the nucleosome remodeling-deacetylase complex (nurd) involved in transcription regulation that may be comprised of (but not limited to) two isoforms mi-2 alpha and mi-2 beta. they can be considered as autoantigens and are commonly associated with systemic autoimmune myopathy dermatomyositis.

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 M33.12 to ICD-9-CMHistory

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

ICD-9-CM
710.3 Dermatomyositis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
359.6 Infl myopathy in oth dis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 M33.12Overview

Is M33.12 (Other dermatomyositis) a billable code?

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

What MS-DRG does M33.12 group to?

When other dermatomyositis with myopathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M33.12?

Under the General Equivalence Mappings, other dermatomyositis with myopathy converts to ICD-9-CM 710.3 (dermatomyositis) and 359.6 (infl myopathy in oth dis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.