Neutrophils in neutrophilic dermatoses: Emerging roles and promising targeted therapies

Neutrophilic dermatoses (NDs) are a heterogeneous group of cutaneous inflammatory diseases characterized by predominant and sterile neutrophilic infiltrates in lesional skin. This neutrophil infiltration varies in degree, leading to manifestations such as pustules, abscesses, papules, nodules, and ulcers, with possible systemic or other organ involvement. NDs are subdivided into 4 groups based on histology1: (1) epidermal type with pustular psoriasis, which is representative; (2) dermal type, including Sweet syndrome; (3) hypodermal type, with pyoderma gangrenosum (PG) as the paradigm; and (4) overlapping type (epidermal, dermal, or hypodermal), referring to emerging PG-associated autoinflammatory syndromes (Table I).