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ICD-10-CM 2027 diagnosis code

M35.81Multisystem inflammatory syndrome

✓ Billable / specificCC — complication/comorbidity

M35.81 is a valid, billable ICD-10-CM code for multisystem inflammatory syndrome. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for PIMS, ICD-10 code for MIS-A, ICD-10 code for MIS-C, ICD-10 code for Multisystem inflammatory syndrome.

Code last changed in FY2021 (effective October 1, 2020). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M35.81

M35.81 is the ICD-10-CM diagnosis code for Multisystem inflammatory syndrome. It belongs to category M35 (other systemic involvement of connective tissue), block M30-M36 (systemic connective tissue disorders) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M35.8 (other specified systemic involvement of connective tissue), M35.81 is specifically for Multisystem inflammatory syndrome. Related codes cover other specified systemic involvement of connective tissue (M35.89).

Code first: , if applicable, COVID-19 (U07.1).

Use an additional code, if applicable, for: exposure to COVID-19 or SARS-CoV-2 infection (Z20.822), personal history of COVID-19 (Z86.16) and post COVID-19 condition (U09.9).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 545 (Connective Tissue Disorders with MCC, relative weight 2.3892), DRG 546 (Connective Tissue Disorders with CC, relative weight 1.1745) and DRG 547 (Connective Tissue Disorders without CC/MCC, relative weight 0.7526), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It was added in FY2021, effective October 1, 2020.

Coding notes

Applicable toConditions and synonyms classified to this code
  • MIS-A
  • MIS-C
  • Multisystem inflammatory syndrome in adults
  • Multisystem inflammatory syndrome in children
  • Pediatric inflammatory multisystem syndrome
  • PIMS
Code firstSequence the underlying condition first
  • , if applicable, COVID-19 (U07.1)
Use additional codeAdd a secondary code to fully describe the condition
  • code, if applicable, for:
  • exposure to COVID-19 or SARS-CoV-2 infection (Z20.822)
  • personal history of COVID-19 (Z86.16)
  • post COVID-19 condition (U09.9)
Code alsoTwo codes may be needed; sequencing depends on circumstances
  • any associated complications such as:
  • acute hepatic failure (K72.0-)
  • acute kidney failure (N17.-)
  • acute myocarditis (I40.-)
  • acute respiratory distress syndrome (J80)
  • cardiac arrhythmia (I47-I49.-)
  • pneumonia due to COVID-19 (J12.82)
  • severe sepsis (R65.2-)
  • viral cardiomyopathy (B33.24)
  • viral pericarditis (B33.23)

Notes that apply from higher levels

Instructions written at a parent level also apply to M35.81.

› From M35 Other systemic involvement of connective tissue
Excludes1
  • reactive perforating collagenosis (L87.1)

Broader instructions also apply from M30-M36 Systemic connective tissue disorders and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Alphabetic index entries

7 entries

Terms in the official ICD-10-CM index that lead to M35.81.

Codes whose notes reference M35.81

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2021 (effective 10/1/2020): Added
  • No changes since FY2021.

Common questions about M35.81

Is M35.81 billable?

Yes. M35.81 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M35.81 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M35.81 as a principal diagnosis.

Is M35.81 a CC or MCC?

M35.81 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does M35.81 group to?

M35.81 is used in the MS-DRG v44.0 logic for MS-DRG 545 (Connective Tissue Disorders with MCC), MS-DRG 546 (Connective Tissue Disorders with CC) and MS-DRG 547 (Connective Tissue Disorders without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.