Herpetiform Sweet's syndrome and leukaemia

A patient who developed atypical vesicular Sweet's syndrome (SS) resembling herpes simplex virus infection, during relapse of acute myeloid leukaemia is presented. The morphologic and histologic spectrum of SS is discussed, alerting dermatologists to atypical varients. The association with malignancy, particularly of myeloprliferative origin, is highlighted, as are features of SS that suggest the presence of an underlying malignancy.