[Neutrophilic dermatoses].

PURPOSE: The neutrophilic dermatoses are a group of skin diseases mainly characterized by an infiltration of the skin by normal polymorphonuclears, without any identifiable (infectious) cause. In this review we describe the main neutrophilic dermatoses and point on their multisystemic dimension. CURRENT KNOWLEDGE AND KEY-POINTS: Well-defined neutrophilic dermatoses are Sweet's syndrome, pyoderma gangrenosum, subcorneal pustular dermatosis, erythema elevatum diutinum and neutrophilic eccrine hidradenitis, as well as newer and rarer conditions such as aseptic abscesses. Clinical overlap between these disorders led to the concept of "the" neutrophilic dermatosis. In addition, patients with a neutrophilic skin disorder may also suffer from extra-cutaneous aseptic neutrophilic infiltrates. This "neutrophilic disease" is often difficult to diagnose. Neutrophilic dermatoses are significantly associated with systemic disease. These include hematological disorders, inflammatory bowel disease, joint immunological disorders, and other malignant or inflammatory conditions. First-line treatment of acute neutrophilic conditions is steroid therapy. In chronic conditions, dapsone is often efficient. FUTURE PROSPECTS AND PROJECTS: The mechanisms underlying the inappropriate activation of polymorphonuclears are poorly understood. Hematopoietic growth factors and adhesion molecules are believed to play a role in the pathophysiology of the neutrophilic dermatoses.