Annular lichen planus and annular atrophic lichen planus

Lichen planus (LP) is characterized clinically by translucid, violaceous, polygonal lesions, and histologically by a band-like infiltrate in the superficial dermis. In 10% of patients with classic LP, annular lesions are found. In males these are seen mainly on the penis. However, exclusively annular lesions are rare. The LP, furthermore, regresses spontaneously or after therapy within some months, with or without a transitory pigmentation. In this paper 6 cases of annular LP are reported. In one of the patients lesions have resolved with hyperpigmentation, while in the other 5 the annular papules have become atrophic configuring the rare variant of annular atrophic LP. The last aspect is due to dermic elastolysis, and consequent disappearance of elastic fibers in lichenoid annular active lesions. The effects of elastolysis, caused by macrophages, are rapidly repaired in the classic LP, while in the annular form probably there is a more intensive elastolysis with extended involvement of the reticulate fibrilles.