Histiocytoid Sweet syndrome treated with azathioprine: a case report.

Histiocytoid Sweet syndrome (HSS) is a rare histologic variation of Sweet syndrome (SS) predominantly exhibiting mononuclear histiocytoid cells instead of neutrophils. We report a 22-year-old woman with HSS, who, after minimal improvement with colchicine and dapsone, had significant improvement of her cutaneous eruption and systemic symptoms following empiric treatment with azathioprine. Since azathioprine has historically been known to cause SS, this case highlights a previously unreported treatment response for the histiocytoid variant.