Acute febrile neutrophilic dermatosis (Sweet syndrome) was initially described by Dr. Robert Douglas Sweet in 1964 and consists of the following four cardinal features: (1) fever; (2) polymorphonuclear leukocytosis of the blood; (3) raised painful plaques on the limbs, face, and neck; and (4) histologic demonstration of a dense dermal infiltration with mature neutrophils. Since the initial description of this syndrome, numerous reports have appeared in the medical literature detailing its wide clinical spectrum and association with other conditions. Clinical conditions to which Sweet syndrome has been definitively related include cancer, infections, inflammatory bowel disease, medications, and pregnancy. Based on the clinical context in which it occurs, Sweet syndrome can be classified as classical (idiopathic), malignancy associated, or drug induced. Specific criteria have been proposed to aid in the diagnosis, with both major and at least two minor criteria required for a definitive diagnosis. The major criteria consist of abrupt onset of tender or painful erythematous plaques or nodules, and predominantly neutrophilic infiltration in the dermis without leukocytoclastic vasculitis. The minor criteria consist of the following: (1) association with an underlying hematological or visceral malignancy, inflammatory disease, or pregnancy, or preceded by an upper respiratory or GI infection or vaccination; (2) pyrexia > 38°C; (3) laboratory values during onset (three of four of the following: (A) erythrocyte sedimentation rate > 20 mm/h, (B) C-reactive protein positive, (C) segmented-nuclear neutrophils and stabs > 70% in peripheral blood smear, (D) leukocytosis > 8,000 cells/μL); and (4) excellent response to treatment with systemic corticosteroids or potassium iodide. Similarly, criteria for drug-induced Sweet syndrome have also been proposed.