EOSINOPHILIC FOLLICULITIS - THE HISTOLOGIC SPECTRUM

We sought to define the light microscopic features of eosinophilic fol liculitis as it occurs in human immunodeficiency virus (HIV)-infected individuals. The histologic findings of 52 biopsies from 50 patients w ere graded and compared with six biopsies of suppurative folliculitis from HIV-infected individuals. In all patients, clinical examination s howed an eruption of pruritic follicular papules, and the folliculocen tric nature of the disorder was confirmed histologically. Perifollicul ar infiltrates of lymphocytes and eosinophils were identified in all s tudy biopsies, and there was also spongiosis of follicular epithelium. The inflammatory reaction was focused at the level of the follicular isthmus and the sebaceous duct. In all biopsies, lymphocytes and/or eo sinophils were present within spongiotic follicular epithelium, but in trafollicular neutrophils were rare. Sebaceous glandular inflammation, eosinophilic pustule formation, and follicular rupture were present i n less than half of the biopsies. Small numbers of microbes (bacteria, yeast, Demodex) were identified in 25% of the study biopsies in routi ne or special stains, but the organisms were away from areas of inflam mation and were interpreted as nonpathogenic flora. The biopsies of su ppurative folliculitis differed in that neutrophils and macrophages pr edominated in the infiltrate, microorganisms were readily identified i n the inflammatory reaction, and the involved follicle was often ruptu red. We believe that eosinophilic folliculitis is a unique HIV-associa ted dermatosis distinguishable from other folliculitides and papular d ermatitides by clinical examination and light microscopy. We present o ur diagnostic approach.