Multisystem Inflammatory Syndrome in Adults (MIS-A)
Although most commonly seen in pediatrics, there have been some cases of a severe hyperinflammatory condition associated with SARS-CoV-2 recognized as multisystem inflammatory syndrome in adults (MIS-A). The current five working criteria for MIS-A include severe illness requiring hospitalization for patients > 21 years of age, positive test for current or previous SARS-CoV-2 infection in the past 12 weeks, severe dysfunction of one or more extrapulmonary organ systems, laboratory evidence of severe inflammation, and absence of severe respiratory illness.[38,39] MIS-A, like MIS-C, may show polymorphic rash. Morris et al. described 16 patients meeting criteria for MIS-A and five with cutaneous manifestations, most notably mucositis, during hospital admission. Additionally, So et al. described two patients with urticarial macules and plaques.
MIS-A associated with SARS-CoV-2 infection is also due to overactive innate immune activation, most likely an aberrant interferon response leading to hyperinflammation causing abnormalities in affected internal organs and skin. Due to limited cases, no molecular mechanistic studies have been done.
Skin biopsy demonstrated superficial perivascular lymphocytic infiltrate with rare neutrophils and extravasated erythrocytes with negative in situ hybridization for SARS-CoV-2 spike protein in a patient with urticarial macules and patches; similarly, another biopsy showed superficial and deep perivascular and periadnexal lymphocytic infiltrate with negative in situ hybridization for SARS-CoV-2 in a different patient with urticarial plaques.
More than half of the patients with MIS-A required intensive care support and had fair-to-unfavorable prognosis. Some required vasopressors, extracorporeal membrane oxygenation, endotracheal intubation, and ventilation. The treatments for MIS-A secondary to SARS-CoV-2 infections include IVIG, corticosteroids, and tocilizumab, an interleukin-6 inhibitor, in addition to intensive care support when needed.[38,40]
Am J Clin Dermatol. 2022;23(3):277-286. © 2022 Adis Springer International Publishing AG