Sweet Syndrome: Clinical Features, Histopathology, and Associations of 83 Cases

Background: Sweet syndrome (SS) is an infrequent skin disease characterised by sudden onset of fever, leukocytosis, neutrophilia, and tender erythematous plaques infiltrated by neutrophils. Multiple conditions have been associated with this syndrome. Objectives: The aim of this study was to evaluate the clinical, epidemiological, laboratory, and histopathological findings and associations of patients with SS. Methods: We conducted a retrospective study of 83 patients with SS followed between January 1, 2006, and January 31, 2015. Results: Of the patients, 82% were female; the mean age at onset was 48 years. Clinical presentation was mainly characterised by erythematous and edematous plaques, mostly on upper extremities and trunk. Fever was observed in 32%; 60% presented leukocytosis and 39% neutrophilia. On histopathological examination, neutrophilic and lymphohistiocytic infiltrate and edema were the most frequent findings. Fourteen percent of patients had malignancy or hematologic disorders, 26% were classified as having drug-induced SS, and 24% noted recent infection. Only 2 cases occurred during pregnancy. Systemic corticosteroid was the most common choice of treatment, with excellent response. In malignancy-associated SS, the mean hemoglobin level was lower (P = .01) and the erythrocyte sedimentation rate (ESR) was higher (P = .04) in comparison to classic and drug-induced SS. Leukocytoclasia was associated with higher risk of recurrence (P = .01). Conclusion: All patients with SS deserve careful investigation of possible underlying conditions. Higher ESR and lower hemoglobin levels might reinforce the need of malignancy screening. Also, leukocytoclasia appears to be a potential marker of higher recurrence rate, demanding closer and longer follow-up.