Sweet´s syndrome: A review and update on new clinical and histological variants

Abstract

Neutrophilic dermatoses involve a diverse range of conditions for which significant findings have been made in recent years. Despite the lack of comprehensive understanding of the pathophysiology of neutrophilic dermatoses, patients with pyoderma gangrenosum and Sweet's syndrome exhibit elevated levels of IL-1β, IL-17 and TNFα in the skin, accompanied by a dysregulation of the innate immune system. Furthermore, autoinflammatory diseases with the presence of neutrophilic infiltrates characteristic of neutrophilic dermatoses have also been described. Sweet's syndrome is a primary dermal neutrophilic dermatosis characterized by the presence of a sterile neutrophilic infiltrate without the presence of vasculitis in the superficial and mid dermis.  This is de clinical form of neutrophilic dermatosis most frequently found in clinical practice. Depending on the etiology, we distinguish classic Sweet's syndrome, Sweet's syndrome associated with neoplasia, pharmacological Sweet's syndrome and Sweet's syndrome associated with lymphoedema. The clinical manifestations of SS are diverse, however cutaneous involvement is the most common organ affected. This typically presents as painful erythematous-edematous plaques or nodules on the upper third of the body. Recently, new variants of neutrophilic dermatoses have been described, which can be divided into clinical and histological variants. The new clinical variants are blistering Sweet's syndrome, cellulitis-like Sweet's syndrome, necrotizing Sweet's syndrome, and neutrophilic dermatosis of the dorsum of the hands. Histological variants found are divided into the next patterns: cryptococcal, histiocytic, subcutaneous/panniculitic, eosinophilic, lymphocytic and xanthomyzed normolipidemic. It is recommended that all patients with neutrophilic dermatoses receive systemic treatment to prevent recurrences, which occur in 30-50% of cases. The first-line treatment should be corticosteroids.