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Multisystem inflammatory syndrome in adults
Other Resources UpToDate PubMed

Multisystem inflammatory syndrome in adults

Contributors: Paritosh Prasad MD, Eric Ingerowski MD, FAAP
Other Resources UpToDate PubMed


A new multisystem inflammatory disorder was identified during the coronavirus disease 2019 (COVID-19) pandemic called multisystem inflammatory syndrome in children (MIS-C) that primarily affects children and presents with some combination of shock, cardiac dysfunction, abdominal pain, and elevated inflammatory markers.

Since June of 2020, similar case reports have been reported in adults, leading to the description of a new clinical disorder named MIS-A, or multisystem inflammatory syndrome in adults. MIS-A should be considered in adults with:
  1. A severe illness requiring hospitalization in a person aged 21 years or older
  2. A positive test result for current or previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (polymerase chain reaction [PCR], antigen, or antibody) during admission or in the previous 12 weeks
  3. Severe dysfunction of one or more extrapulmonary organ systems (shock, cardiac dysfunction, arterial or venous thrombosis or thromboembolic disease, or acute liver injury)
  4. Laboratory evidence of severe inflammation (elevations in C-reactive protein [CRP], ferritin, D-dimer, or interleukin 6 [IL-6])
  5. Absence of severe respiratory illness (to exclude patients with severe COVID-19 where organ dysfunction may be due to hypoxia, where oxygen demand outstrips oxygen supply resulting in ischemic injury). The presence of mild respiratory symptoms does not disqualify a patient from the diagnosis, although alternative etiologies of shock such as bacterial sepsis would exclude a patient.
A total of 16 individual case reports and 3 case series have been published of patients meeting criteria for MIS-A. These patients were aged 20-50 years, with a roughly equal ratio of men to women (7 men, 9 women) in the individual case reports; 9 of the 16 case report patients were African American, 1 was of African descent born in the United Kingdom, 5 were of Hispanic descent, and 1 was of Asian descent. This was similar to the ethnic breakdown of the one case series that reported ethnicity in which 2 of 7 reported patients were African American, 2 were of Hispanic descent, and 2 were of Middle Eastern descent, with 1 reported as White. About half of the case report patients (9 of 16) had no reported past medical history, 6 were obese, 1 had type 2 diabetes, 2 had hypertension, and 1 had obstructive sleep apnea. One-half of case report patients had a documented respiratory illness prior to developing symptoms of MIS-A, and one-half did not.

Seventy-five percent of case report patients (12 of 16) had fever > 100.4°F (38°C) for over 24 hours or reported subjective fevers for greater than 24 hours upon presentation; 6 of these 16 had chest pain or palpitations, and all 16 had cardiac effects such as cardiac arrhythmias, elevated troponin levels, or echocardiographic evidence of ventricular dysfunction. Thirteen of the sixteen had gastrointestinal symptoms on admission, and 5 had dermatologic findings, 3 of whom had mucositis. While most did not have significant respiratory symptoms, 10 of 16 had ground glass opacities noted on chest CT, and 6 had pleural effusions.

All patients described with MIS-A had elevated inflammatory makers including elevated CRP, ferritin, and D-dimers. Ten of the sixteen were also found to be leukopenic.

With respect to SARS-CoV-2 testing, 10 of the 16 case reports were positive for SARS-CoV-2 by PCR at the time of initial assessment for MIS-A. Of these 10, 7 also had positive SARS-CoV-2 antibody (Ab) testing. Six had negative SARS-CoV-2 PCR, of whom four had positive SARS-CoV-2 Ab testing. Five of the sixteen had documentation of SARS-CoV-2 PCR positivity in the preceding weeks, ranging from 14 to 41 days prior to presentation with MIS-A.

Treatment is largely supportive, although patients have received intravenous (IV) immunoglobulin (IVIG), corticosteroids, or tocilizumab (IL-6 inhibitor). There is very little evidence available to guide the use of these immunomodulatory therapies in MIS-A.

While it is difficult to assess the mortality of the condition given the limited number of published cases, at least 2 of the 16 case report patients ultimately succumbed to the illness.

Related topic: postacute COVID-19 syndrome (long COVID-19)


M35.81 – Multisystem inflammatory syndrome

1119306006 – Multisystem inflammatory syndrome in adults

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Last Reviewed:11/04/2020
Last Updated:07/25/2021
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Multisystem inflammatory syndrome in adults
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