Multisystem inflammatory syndrome in an adult with severe hypoxaemia and thyroiditis responsive to corticosteroid and interleukin 6 inhibitor treatment.

Multisystem inflammatory syndrome in adults (MIS-A) has been reported as a rare but severe consequence of COVID-19 infection. Adult patients were more likely to present with hypotension and cardiac illness when compared with multisystem inflammatory syndrome in children. Although the exact prevalence of MIS-A is unknown, more cases have been observed in men and younger adults. The pathophysiology of MIS-A is also unclear, but is thought to be caused by a delayed, dysregulated immune response. Given no established guideline for treatment of MIS-A, treatment has been based on case reports. We present a case of MIS-A in a woman in her 60s who had severe hypotension, progressive dyspnoea, massive pleural effusion, hypoxaemia, thyroiditis and multiple organ failure, which dramatically improved after treatment with corticosteroid and interleukin 6 inhibitor.