Epidermal repair in lichen planus: a light and electron microscopical study*

Sequential analysis of epidermal repair following experimental injury has been undertaken in four patients with lichen planus. Linear incisions were made through the full epidermal thickness of eight papules and were subsequently biopsied and processed for light and electron microscopy, after intervals of 1–5 days. Large migrating cells with abundant phagolysosomes were present in the superficial viable layers of the cut edges of the epidermis at 24 h after wounding. By 2 days following injury, re‐epithelialization of the wounds had occurred and mitotic figures were present in the lesional epidermis at the wound margins. By 5 days, differentiation and maturation of the newly formed epithelium had progressed to a point where and healing tissue was almost indistinguishable from the surrounding epidermis. These findings indicate that the epidermis in lichen planus has the ability to respond briskly and effectively to wounding and that cell replacement appears to come from within the lesional tissue. Intracytoplasmic desmosomes and gap junction were observed within the epidermal cells throughout the course of the study. The significance of these latter observations is discussed.