**2. Definition and classification**

SS is a neutrophilic dermatosis characterized by specific clinical and histopathological manifestations. In fact, the best way of defining SS is based on its diagnostic criteria. Typically, SS appears abruptly with multiple, edematous, tender red plaques that are distributed bilaterally but asymmetrically in a febrile patient. The dermatopathological image shows a neutrophilic diffuse infiltrate without vasculitis located in upper dermis. Besides this typical picture, several clinical and histopathological variants have been described (table 1). The current classification of SS is based on the associated or trigger conditions and has clinical value for the management of these patients (table 2).

Transitional forms with other neutrophlic dermatosis Located forms: dorsal hands and facial Chronic recurrent neutrophilic dermatosis Histiocytoid Sweet syndrome

Table 1. Main clinical and histopathological subtypes of Sweet syndrome

Idiopatic Parainflammatory Paraneoplastic Drug-induced Associated to pregnancy

Table 2. Classification of Sweet syndrome

Sweet Syndrome 121

Fig. 1. Erythematous plaques with vesicular and bullous appearance due to a intense dermal

Fig. 2. The plaques on tenar and hypotenar skin have frequently a characteristic appearance

The mucous membranes are frequently involved, especially the ocular as conjunctivitis or epiescleritis (Gottlieb et al, 2008) (figure 3). Less frequent is the affectation of the oral

edema.

of "montain range"

**5.2 Mucous membranes** 

mucosa, usually as aphtous ulcers.
