M35.81: Multisystem inflammatory syndrome
M35.81, multisystem inflammatory syndrome, is listed as a covered diagnosis in 8 Medicare billing and coding articles that apply to 26 HCPCS Level II codes, including J1569 (Injection, immune globulin, (gammagard liquid/gammagard…), J1561 (Injection, immune globulin, (gamunex-c/gammaked)…), J1459 (Injection, immune globulin (privigen), intravenous…). The articles come from 5 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with M35.81 as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| J1569 | Injection, immune globulin, (gammagard liquid/gammagard liquid erc), 500 mg | Special coverage instructions apply | — | 2 |
| J1561 | Injection, immune globulin, (gamunex-c/gammaked), non-lyophilized (e.g., liquid), 500 mg | Special coverage instructions apply | — | 2 |
| J1459 | Injection, immune globulin (privigen), intravenous, non-lyophilized (e.g., liquid), 500 mg | Carrier judgment | — | 2 |
| J1557 | Injection, immune globulin, (gammaplex), intravenous, non-lyophilized (e.g., liquid), 500 mg | Carrier judgment | — | 2 |
| J1556 | Injection, immune globulin (bivigam), 500 mg | Carrier judgment | — | 2 |
| J1568 | Injection, immune globulin, (octagam), intravenous, non-lyophilized (e.g., liquid), 500 mg | Carrier judgment | — | 2 |
| J1566 | Injection, immune globulin, intravenous, lyophilized (e.g., powder), not otherwise specified, 500 mg | Special coverage instructions apply | — | 2 |
| J1554 | Injection, immune globulin (asceniv), 500 mg | Carrier judgment | — | 2 |
| J1599 | Injection, immune globulin, intravenous, non-lyophilized (e.g., liquid), not otherwise specified, 500 mg | Carrier judgment | — | 2 |
| J1577 | Injection, immune globulin (qivigy), 100 mg | Carrier judgment | — | 2 |
| J1576 | Injection, immune globulin (panzyga), intravenous, non-lyophilized (e.g., liquid), 500 mg | Special coverage instructions apply | — | 1 |
| J1745 | Injection, infliximab, excludes biosimilar, 10 mg | Special coverage instructions apply | — | 1 |
| Q5104 | Injection, infliximab-abda, biosimilar, (renflexis), 10 mg | Special coverage instructions apply | — | 1 |
| Q5103 | Injection, infliximab-dyyb, biosimilar, (inflectra), 10 mg | Special coverage instructions apply | — | 1 |
| Q5121 | Injection, infliximab-axxq, biosimilar, (avsola), 10 mg | Carrier judgment | — | 1 |
| J1575 | Injection, immune globulin/hyaluronidase, (hyqvia), 100 mg immuneglobulin | Carrier judgment | — | 1 |
| J1572 | Injection, immune globulin, (flebogamma/flebogamma dif), intravenous, non-lyophilized (e.g., liquid), 500 mg | Special coverage instructions apply | — | 1 |
| J1460 | Injection, gamma globulin, intramuscular, 1 cc | Special coverage instructions apply | — | 1 |
| J1670 | Injection, tetanus immune globulin, human, up to 250 units | Special coverage instructions apply | — | 1 |
| J0840 | Injection, crotalidae polyvalent immune fab (ovine), up to 1 gram | Carrier judgment | — | 1 |
| J0850 | Injection, cytomegalovirus immune globulin intravenous (human), per vial | Special coverage instructions apply | — | 1 |
| J1552 | Injection, immune globulin (alyglo), 500 mg | Carrier judgment | — | 1 |
| J1560 | Injection, gamma globulin, intramuscular, over 10 cc | Special coverage instructions apply | — | 1 |
| J1571 | Injection, hepatitis b immune globulin (hepagam b), intramuscular, 0.5 ml | Special coverage instructions apply | — | 1 |
| J1573 | Injection, hepatitis b immune globulin (hepagam b), intravenous, 0.5 ml | Carrier judgment | — | 1 |
1 more codes are listed. See every code with payment by region in Caduvo.
Medicare policy articles listing M35.81
- A59105: Billing and Coding: Off-Label Use of Intravenous Immune Globulin (IVIG) (Wellpoint Federal (MAC - Part A, MAC - Part B); 11 Level II codes). LCD with the same title: L39314
- A52423: Billing and Coding: Infliximab and biosimilars (Wellpoint Federal (MAC - Part A, MAC - Part B); 4 Level II codes)
- A57307: Billing and Coding: Nerve Conduction Studies and Electromyography (CGS Administrators, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57478: Billing and Coding: Nerve Conduction Studies and Electromyography (WPS Insurance Corporation (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57554: Billing and Coding: Immune Globulins (WPS Insurance Corporation (MAC - Part A, MAC - Part B); 20 Level II codes). LCD with the same title: L34771
- A54969: Billing and Coding: Nerve Conduction Studies and Electromyography (Noridian Healthcare Solutions, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57668: Billing and Coding: Nerve Conduction Studies and Electromyography (Wellpoint Federal (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56619: Billing and Coding: Nerve Conduction Studies and Electromyography (Palmetto GBA (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other M35 diagnoses (Other systemic involvement of connective tissue)
- M35.89 — Other specified systemic involvement of connective tissue
- M35.02 — Sjogren syndrome with lung involvement
- M35.03 — Sjogren syndrome with myopathy
- M35.04 — Sjogren syndrome with tubulo-interstitial nephropathy
- M35.05 — Sjogren syndrome with inflammatory arthritis
- M35.06 — Sjogren syndrome with peripheral nervous system involvement
- M35.07 — Sjogren syndrome with central nervous system involvement
- M35.08 — Sjogren syndrome with gastrointestinal involvement
- M35.09 — Sjogren syndrome with other organ involvement
- M35.0A — Sjogren syndrome with glomerular disease
- M35.0B — Sjogren syndrome with vasculitis
- M35.2 — Behcet's disease
- M35.3 — Polymyalgia rheumatica
- M35.4 — Diffuse (eosinophilic) fasciitis
- M35.7 — Hypermobility syndrome
Frequently asked questions
Does Medicare cover M35.81 (Multisystem inflammatory syndrome)?
Medicare covers items and services, not diagnoses. 8 Medicare billing and coding articles list M35.81 as a covered diagnosis for 26 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 M35.81?
The Level II codes from the policies most specific to this diagnosis are J1569 (Injection, immune globulin, (gammagard liquid/gammagard…, 2 articles); J1561 (Injection, immune globulin, (gamunex-c/gammaked)…, 2 articles); J1459 (Injection, immune globulin (privigen), intravenous…, 2 articles); J1557 (Injection, immune globulin, (gammaplex), intravenous…, 2 articles); J1556 (Injection, immune globulin (bivigam), 500 mg, 2 articles). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list M35.81?
A59105 (Billing and Coding: Off-Label Use of Intravenous Immune Globulin (IVIG)); A52423 (Billing and Coding: Infliximab and biosimilars); A57307 (Billing and Coding: Nerve Conduction Studies and Electromyography), and 5 more articles.
What is ICD-10-CM code M35.81?
M35.81 is the ICD-10-CM code for multisystem inflammatory syndrome, in category M35 (Other systemic involvement of connective tissue), chapter 13: Diseases of the musculoskeletal system and connective tissue.
Next steps
- Run a reimbursement report for a device billed under J1569
- Watch J1569 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for J1569
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 13: Diseases of the musculoskeletal system and connective tissue · All diagnoses · HCPCS lookup