Psoriasiform Plaques as a Cutaneous Clue to Persistent Inflammation in Infantile Kawasaki Disease.

Kawasaki disease is typically associated with a polymorphous exanthem, but persistent psoriasiform or pustular plaques during the acute illness may be mistaken for infection, drug eruption, or a separate inflammatory dermatosis. We report a 4-month-old boy with Kawasaki disease who developed erythematous scaly plaques with pustules during the acute phase, in temporal association with recurrent mucosal inflammation and evolving coronary artery dilation requiring repeat intravenous immunoglobulin. Skin biopsy showed psoriasiform epidermal hyperplasia with parakeratosis, loss of the granular layer, neutrophilic exocytosis, papillary dermal edema, and dilated capillaries, supporting psoriasiform dermatitis in the setting of Kawasaki disease. This case highlights the value of clinicopathologic correlation when atypical plaques arise in Kawasaki disease and suggests that such eruptions should prompt careful assessment for ongoing systemic inflammation and coronary involvement.