2026 ICD-10-CM Diagnosis Code M33.10Other dermatomyositis, organ involvement unspecified

ICD-10-CM Codes›M00–M99›M30-M36›M33

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

M33.10 is a billable ICD-10-CM diagnosis code for other dermatomyositis, organ involvement unspecified. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 15 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders.

For Medicare Advantage risk adjustment, M33.10 maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the V28 model, adding a risk factor of about 0.617 for a community, non-dual, aged beneficiary in payment year 2026.

Code Identity

ICD-10-CM Code
M33.10
Billable Status
Yes — Valid for Submission
Code Describes
Other dermatomyositis, organ involvement unspecified
Short Description
Other dermatomyositis, organ involvement unspecified
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 CodeM33.10Other dermatomyositis, organ involvement unspecified

Medicare Risk Adjustment (HCC)Billing

M33.10 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.

CMS-HCC V28 Category (Payment Model)
HCC 93— Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
Payment HCC · PY 2026 one of 508 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.617
community, non-dual, aged · ranges 0.288–0.617 across segments
Hierarchy
Supersedes HCC 94
less severe related categories are not paid alongside HCC 93
Prior Model (CMS-HCC V24)
HCC 40
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 40 · ESRD (V21): HCC 40 · ESRD (V24): HCC 40
ESRD V21 weights: 0.072 dialysis, 0.274–0.398 functioning graft · ESRD V24 weights: 0.058 dialysis, 0.284–0.414 functioning graft
Part D (RxHCC)
RxHCC 83 — Rheumatoid Arthritis and Other Inflammatory Polyarthropathy
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adult onset dermatomyositis
  • Antisynthetase syndrome
  • Anti-synthetase syndrome due to dermatomyositis
  • Autoimmune inflammation of skeletal muscle
  • Calcinosis due to adult type dermatomyositis
  • Connective tissue disease overlap syndrome
  • Dermatitis of the newborn
  • Neonatal dermatomyositis
  • Overlap syndrome
  • Poikilodermatomyositis
  • Sclerodermatomyositis

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

Clinical InformationClinical

  • Exosome Component 10|Autoantigen PM-SCL|Autoantigen PM/Scl|EC 3.1.13.-|EXOSC10|P100 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl-100|Polymyositis/Scleroderma Autoantigen 100 kDa|Polymyositis/Scleroderma Autoantigen 2

    exosome component 10 (885 aa, ~101 kda) is encoded by the human exosc10 gene. this protein plays a role in the maturation and degradation of rna.

  • Other Overlap Syndromes|Other overlap syndromes

    evidence of other overlap syndromes not specified elsewhere.

  • Overlap Syndrome

    an autoimmune, connective tissue disorder in which the patient exhibits features from two or more diseases. these typically include systemic sclerosis, dermatomyositis, polymyositis, rheumatoid arthritis, systemic lupus erythematosus, and sjogren syndrome; in pediatrics the respective pediatric entities are encountered.

  • Scleroderma Polymyositis Overlap Syndrome|Scleroderma Polymyositis

    a rare autoimmune disorder in which patients present with overlapping symptoms of systemic scleroderma and polymyositis or dermatomyositis.

  • Exosome Complex Component RRP45|AMPA RECEPTORS|Autoantigen PM/Scl 1|EXOSC9|Exosome Component 9|GLuRs|P75 Polymyositis-Scleroderma Autoantigen|P75 Polymyositis-Scleroderma Overlap Syndrome Associated Autoantigen|P75 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl-75|Polymyositis/Scleroderma Autoantigen 1|Polymyositis/Scleroderma Autoantigen 75 kDa

    exosome complex component rrp45 (439 aa, ~49 kda) is encoded by the human exosc9 gene. this protein is involved in the regulation of the exoribonuclease activity of the exosome.

  • Exosome Component 10|Autoantigen PM-SCL|Autoantigen PM/Scl|EC 3.1.13.-|EXOSC10|EXOSC10|P100 POLYMYOSITIS-SCLERODERMA AUTOANTIGEN|P100 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl 2|PM/Scl-100|PM/Scl-100|Polymyositis/Scleroderma Autoantigen 100 kDa|Polymyositis/Scleroderma Autoantigen 2|Polymyositis/Scleroderma Autoantigen 2

    exosome component 10 (885 aa, ~101 kda) is encoded by the human exosc10 gene. this protein plays a role in the maturation and degradation of rna.

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 M33.10 to ICD-9-CMHistory

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

ICD-9-CM
710.3 Dermatomyositis
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 M33.10Overview

What is the ICD-10 code for other dermatomyositis, organ involvement unspecified?

The ICD-10-CM code for other dermatomyositis, organ involvement unspecified is M33.10 (sometimes written as M3310). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is M33.10 (Other dermatomyositis) a billable code?

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

What MS-DRG does M33.10 group to?

When other dermatomyositis, organ involvement unspecified 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.

Is M33.10 a CC or MCC?

CMS lists M33.10 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 15 closely related codes in its exclusion list.

What is the ICD-9 equivalent of M33.10?

Under the General Equivalence Mappings, other dermatomyositis, organ involvement unspecified converts to ICD-9-CM 710.3 (dermatomyositis). The mapping is approximate, so confirm the match fits the documentation.

What HCC is M33.10?

M33.10 (other dermatomyositis, organ involvement unspecified) maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), commonly written as HCC 93, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 40 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 83.

Does M33.10 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, M33.10 adds a risk adjustment factor of about 0.617 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.288 to 0.617 depending on the payment segment). HCC 93 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 93 category page.