What Is Lichenoid Dermatitis?

Abstract

Interface dermatitis refers to disorders in which the primary site of pathology is the interface between the epidermis and the dermis, that is, the dermo-epidermal junction. Interface dermatitis is divided into two subgroups: vacuolar and lichenoid. The prototype of lichenoid interface dermatitis is lichen planus (LP).

Lichenoid dermatitis is a histological term that refers to a combination of histological findings that is close to those of LP. Disorders in this category include those with a superficial infiltrate and disorders in which the infiltrate extends to the deep plexus. The former include lichenoid drug eruption (which is often photoinduced), lichen nitidus, lichenoid keratosis, lichenoid capillaritis (lichen aureus), lichenoid mycosis fungoides, pityriasis lichenoides, and keratosis lichenoides chronica. The latter include lichenoid lupus erythematosus and lichen striatus.

The histological diagnosis of lichenoid dermatitis is a beginning rather than an end. A search for the underlying clinical disorder requires efforts by both the practitioner and the pathologist.