What is ICD-10 code M33.19?

M33.19 is the ICD-10-CM diagnosis code for Other dermatomyositis with other organ involvement. A rare autoimmune disease with skin rash and inflammation affecting organs other than muscles, such as the lungs, heart, or gastrointestinal system. M33.19 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M33.19 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. M33.19 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M33.19 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does M33.19 map to under V28?

M33.19 maps to CMS-HCC V28 HCC 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM M33.19: Other dermatomyositis

M33.19 maps to CMS-HCC V28 93. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupM33.19

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Systemic connective tissue disorders (M30-M36)

M33.19

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Other dermatomyositis with other organ involvement

A rare autoimmune disease with skin rash and inflammation affecting organs other than muscles, such as the lungs, heart, or gastrointestinal system.

Buddy Insight

Adult dermatomyositis with other organ involvement beyond respiratory or muscle systems indicates complex multi-system disease requiring specialized management.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 93

Rheumatoid Arthritis and Othe...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 056

HHS-HCC 056 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 40

Rheumatoid Arthritis and Infl...

Code-level coefficient reference

RXHCC

Mapped

HCC 83

Rheumatoid Arthritis and Othe...

Code-level coefficient reference

Code Book Path

Official

M33Dermatopolymyositis M33.1Other dermatomyositis M33.19Other dermatomyositis with other organ involvement

Inclusion Terms

Official

Adult dermatomyositisInherited from M33.1

Excludes 2

Official

arthropathic psoriasis (L40.5-)Inherited from M00-M99
certain conditions originating in the perinatal period (P04-P96)Inherited from M00-M99
certain infectious and parasitic diseases (A00-B99)Inherited from M00-M99
compartment syndrome (traumatic) (T79.A-)Inherited from M00-M99
complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from M00-M99
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from M00-M99
endocrine, nutritional and metabolic diseases (E00-E88)Inherited from M00-M99
injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from M00-M99
neoplasms (C00-D49)Inherited from M00-M99
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from M00-M99

Related Codes

Official

M33.10Other dermatomyositis, organ involvement unspecified M33.11Other dermatomyositis with respiratory involvement M33.12Other dermatomyositis with myopathy M33.13Other dermatomyositis without myopathy

Includes

Official

autoimmune disease NOSInherited from M30-M36
collagen (vascular) disease NOSInherited from M30-M36
systemic autoimmune diseaseInherited from M30-M36
systemic collagen (vascular) diseaseInherited from M30-M36

Excludes 1

Official

autoimmune disease, single organ or single cell-type -code to relevant condition categoryInherited from M30-M36

Code First

Official

No Code First sequencing instructions are included in this display for M33.19. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for M33.19. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for M33.19. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed adult dermatomyositis diagnosis

Documentation of specific non-respiratory, non-muscle organ involvement

Evidence of organ dysfunction or inflammation

Assessment of disease activity across organ systems

MEAT Support

HCC Buddy guidance

Confirmed adult dermatomyositis diagnosis

Documentation of specific non-respiratory, non-muscle organ involvement

Evidence of organ dysfunction or inflammation

Assessment of disease activity across organ systems

Audit Caution

HCC Buddy guidance

Using juvenile codes for adult patients

Missing specific organ system documentation

Using when respiratory or muscle involvement is primary

Failing to code specific organ complications separately

Common Mistakes

HCC Buddy guidance

M33.09 — Use for juvenile dermatomyositis with other organ involvement

M33.11 — Use specifically for respiratory involvement

M33.12 — Use specifically for myopathy

M33.10 — Use when organ involvement is unspecified

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is M33.19 an HCC code?

Yes. M33.19 (Other dermatomyositis with other organ involvement) maps to HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.617. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: M33.19 is billable and maps to V28 HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: M33.19
Description: Other dermatomyositis with other organ involvement
HCC (V28): HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
RAF reference coefficient: 0.617
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders

0.617

ESRDHCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

Not separately weighted

RxHCCHCC 83, Rheumatoid Arthritis and Other Inflammatory Polyarthropathy

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work M33.19 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for M33.19

For M33.19, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

M33.19 is the ICD-10-CM diagnosis code for other dermatomyositis with other organ involvement. A rare autoimmune disease with skin rash and inflammation affecting organs other than muscles, such as the lungs, heart, or gastrointestinal system. M33.19 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering systemic connective tissue disorders (m30-m36).

Under the CMS-HCC V28 risk adjustment model, M33.19 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (HCC 93) with a source-labeled community, non-dual, aged reference coefficient of 0.617. No V24 mapping is shown for M33.19; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Document which specific organ systems are involved beyond skin manifestations. For M33.19, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for M33.19 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document which specific organ systems are involved beyond skin manifestations
•Review for involvement of lungs, heart, GI tract, or other organs and code accordingly

Clinical Significance

Adult dermatomyositis with other organ involvement beyond respiratory or muscle systems indicates complex multi-system disease requiring specialized management. These patients often have higher morbidity and require coordination between multiple subspecialties.