Abstract

Folliculitis is an inflammatory reaction in the superficial aspect of the hair follicle and can involve the follicular opening or the perifollicular hair follicles. The pilosebaceous unit of the follicle is divided into three compartments: the infundibulum (superficial part, outlined by the sebaceous duct), the isthmus (between the sebaceous duct and arrector pili protuberance), and the inferior segment (stem and hair bulb). This anatomical scheme forms the basis for any evaluation of the clinical manifestations of folliculitis. Most of the follicular conditions can be classified according to their anatomical location and histopathologic patterns. Clinically, the inflammation manifests as 1mm-wide vesicles, pustules, or papulopustules in acute cases; however, hyperkeratosis and keratotic plug formations are indicative of a chronic process. The presence of superficial pustules does not always imply an infectious origin, as there are many noninfectious types of folliculitis. In this review, we describe the different types of folliculitis based on their etiology, clinical manifestation, and treatment. We also discuss some newly described disorders and the latest information on their treatment.