[Acute febrile neutrophilic dermatosis (Sweet syndrome). A retrospective clinical and histological analysis].

Acute febrile neutrophilic dermatosis (Sweet's syndrome) was first described in 1964. The condition presents with rapidly developing inflammatory plaques, a neutrophilic dermal infiltrate, fever and leucocytosis. In this study, clinical and histological features of 18 patients with Sweet's syndrome have been analysed. The arms (83%), face (67%) and legs (67%) were the most common sites of involvement. Morphologically, plaques, nodes and pseudo-vesicles prevailed. Elevated ESR (89%), fever (72%) and peripheral blood leucocytosis (44%) were noted in many, but not all, cases. Histology revealed a dermal infiltrate with numerous neutrophils (100%) without vasculitis. Nuclear dust (72%) and extravasation of erythrocytes (44%) were also encountered. Collagen degeneration was not observed. Differential diagnosis included erythema multiforme, erythema nodosum and adverse drug reaction. Possible causative factors observed were upper respiratory tract infection, gastrointestinal infection, and malignancies. Sweet's syndrome may be considered as an extreme manifestation within a continuous spectrum of cutaneous reactions to various stimuli or as an ill-defined entity that has some overlap with other dermatoses.