Sweet's syndrome: study of 73 cases, emphasizing histopathological findings.

BACKGROUND Sweet's syndrome refers to a set of cutaneous, systemic and histopathological alterations that occur in response to different stimuli, in a similar way to that occurring in erythema nodosum, erythema multiforme and leukocytoclastic vasculitis. The syndrome has been described in association with conditions such as infections, pregnancy, the use of certain medications and malignancy. OBJECTIVES To evaluate the clinical and histopathological alterations occurring in this syndrome and to assess the association between these alterations and other conditions. METHODS A retrospective study of 73 cases was conducted, evaluating data on the microscopic examination of skin lesions, as well as clinical and laboratory data. RESULTS The majority of the patients were female (83.0%), white (49.2%) and between 30 and 60 years of age (73.8%). The principal alterations found were: erythymatous plaques (76.9%), papules (43.0%), pseudo-vesiculation (PV) (38.4%) and target lesions (18.5%). With respect to the associated conditions, upper respiratory tract infections (15.4%) and the use of medication (10.8%) were the most common. Other associations, albeit represented by only one case each, were: Hodgkin's lymphoma, pregnancy, ulcerative colitis, polycythemia vera and lupus erythematosus in a patient with acquired immune deficiency syndrome (AIDS). The principal microscopic findings were: neutrophils with leukocytoclasia (98.6%), collagen degeneration (87.7%), edema (74.0%) and PV (38.4%). The presence of eosinophils (41.1%) ranged from rare to abundant and was usually unrelated to the use of medication. Inflammatory infiltrate reached the deep epidermal layer in 47.9% of cases and panniculitis was found in 80.0% of cases in which the hypodermis was affected (10 cases). CONCLUSIONS In general, these findings are in agreement with results published in the literature, emphasizing the frequent finding of eosinophils unrelated to drug use, panniculitis and the rare association with Hodgkin's lymphoma. This is the fifth report of an association between Sweet's syndrome and Hodgkin's disease.