Lichenoid folliculitis: A unifying concept.

Skin diseases presenting with keratotic papules, atrophy, cicatricial alopecia and/or "lichenoid" histopathologic changes have been described under at least 30 names. This family of diseases contains 2 subgroups, largely based on clinical features: keratosis pilaris atrophicans (KPA; including keratosis pilaris atrophicans faciei/ulerythema ophryogenes, atrophoderma vermiculatum, and keratosis follicularis spinulosa decalvans); and the lichen planopilaris (LPP) subgroup (including LPP, frontal fibrosing alopecia, Graham-Little-Piccardi-Lassueur Syndrome and fibrosing alopecia in a pattern distribution). An interface dermatitis with lichenoid inflammation is characteristic of the LPP group of disorders, but the literature provides scant information about the histopathology of the KPA group. Our experience has been that the 2 subgroups show a unifying histologic similarity as well as considerable clinical overlap. Because these conditions overlap clinically and histologically, we propose that the term lichenoid folliculitis (LF) be used to refer to this group of diseases, thus simplifying cumbersome nomenclature and highlighting the possibility of shared pathogenesis and treatment options.