Urticarial vasculitis: A potential signpost for multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) is a rare and serious complication of Sars-Cov-2 infection. Dermatologic manifestations are present in the majority of patients. Skin lesions found in children with MIS-C are classified into four categories: morbilliform, reticulated, scarlatiniform, and urticarial lesions. Clinicopathologic characterization within these categories is limited. Thus, we present a clear example of an urticarial lesion in the context of MIS-C with well-documented clinicopathologic phenomena. A previously healthy 16-year-old female presented with 3 weeks of an itchy, burning rash initially presenting on her right forearm (and lasting greater than 24 hours without migration) before spreading diffusely. She also reported fever, cough, myalgias, nausea, and vomiting of 4 weeks' duration. Physical examination revealed an edematous, maculopapular, nonblanching, erythematous rash covering the patient's upper extremities, abdomen, back, anterior thighs, and face. The patient tested positive for COVID-19. A low-grade leukocytoclastic vasculitis was noted along with intraluminal fibrin and rare microthrombi in vessels of the mid to deep dermis. The patient was diagnosed with MIS-C and urticarial vasculitis. She was treated with steroids and naproxen for subsequent MIS-C flares. Dapsone treatment was started for the urticarial vasculitis.