[Perforating folliculitis].

We report the case of a 20-year old male patient without significant familial or personal history who presented with a disseminated papular eruption on the abdomen, flanks and buttocks. The eruption was continual and proceeded by outbreaks, but it was not influenced by seasons. Physical examination of the skin, mucosae and skin appendages was otherwise normal. Histological examination showed all the criteria of perforating folliculitis as described by Mehregan and Coskey. On the basis of our case we would put perforating folliculitis back among the perforating dermatoses. The concept of this curious phenomenon is briefly reviewed; perforating folliculitis is part of the third group of the so-called primary forms. The clinical features are suggestive of the disease, with its small pigmented papules centred around a keratotic plug, forming a permanent disseminated eruption. Histology shows a granuloma facing a lateral perforation of the hair follicle, a pseudo-epitheliomatous epithelial hyperplasia and the presence of hair and keratin debris in the perforation. Various keratolytic treatments have been applied without success; retinoids have not been tried. The main diagnostic and nosological problem is Kyrle's disease. In view of clinical and histological data, many authors regard Kyrle's disease as a major form of perforating folliculitis. Pruritus, ascribed to an underlying illness in Kyrle's disease, is thought to increase the importance of the lesions. The specificity of perforating folliculitis is discussed, but it seems that side by side with secondary forms occurring in recognized diseases, there may be primary forms of perforating folliculitis. Dyskeratosis might be a cause of the perforation.