Febrile neutrophilic dermatosis

Sweet syndrome (SS), or acute febrile neutrophilic dermatosis, is a skin disease characterized by the sudden onset of fever, an elevated white blood cell count, and tender, red, well-demarcated papules and plaques that show dense infiltrates by neutrophil granulocytes on histologic examination. The syndrome was first described in 1964 by Robert Douglas Sweet. It was also known as Gomm–Button disease in honour of the first two patients Sweet diagnosed with the condition. Acute, tender, erythematous plaques, nodes, pseudovesicles and, occasionally, blisters with an annular or arciform pattern occur on the head, neck, legs, and arms, particularly the back of the hands and fingers. The trunk is rarely involved. Fever (50%); arthralgia or arthritis (62%); eye involvement, most frequently conjunctivitis or iridocyclitis (38%); and oral aphthae (13%) are associated features. SS can be classified based upon the clinical setting in which it occurs: classical or idiopathic SS, malignancy-associated SS, and drug-induced SS. SS is a reactive phenomenon and should be considered a cutaneous marker of systemic disease. Careful systemic evaluation is indicated, especially when cutaneous lesions are severe or hematologic values are abnormal. Approximately 20% of cases are associated with malignancy, predominantly hematological, especially acute myelogenous leukemia (AML). An underlying condition (streptococcal infection, inflammatory bowel disease, nonlymphocytic leukemia and other hematologic malignancies, solid tumors, pregnancy) is found in up to 50% of cases. Attacks of SS may precede the hematologic diagnosis by 3 months to 6 years, so that close evaluation of patients in the “idiopathic” group is required. There is now good evidence that treatment with hematopoietic growth factors—including granulocyte colony-stimulating factor (G-CSF), which is used to treat neutropenia, and granulocyte-macrophage colony-stimulating factor—can cause SS. Lesions typically occur when the patient has leukocytosis and neutrophilia but not when the patient is neutropenic.