Annular lichen planus showing a change in metallothionein expression on immunohistochemistry

The immunohistochemical localization of metallothioneins (MTs), low-molecular-weight metal-binding proteins, was investigated in a case of annular lichen planus (LP) that enlarged centrifugally with healing in the centre after a month. The annular lesion was found to exhibit the early, developed and late stages of LP, as judged by the clinical and histopathological findings. Immunostaining for MTs was increased around the lesion, discontinuous around the rim of the erythema and undetectable in the centre of the lesion. MT expression was examined in eight specimens of idiopathic LP. Discontinuous immunostaining for MTs was observed in six specimens and increased staining around the lesion was observed in two specimens. These results suggest that MT expression changes depending on the inflammatory stage of LP. Although the role of MTs in dermatological disease is still unknown, their expression might be related to the pathological process of LP.