Bullous lichen planus and lichen planus pemphigoides--clinico-pathological comparisons.

Two patients with lichen planus pemphigoides and two with bullous lichen planus were compared. Lichen planus pemphigoides was clinically distinguished by a more generalized lichen planus, more extensive blistering, the need for systemic corticosteroids and by a longer course. The blister of bullous lichen planus was a subepidermal bulla showing degeneration of the epidermal basal layer and other features of lichen planus, whereas in lichen planus pemphigoides the bulla was similar to that of bullous pemphigoid albeit with rather more neutrophils than are usually seen. Direct immunofluorescence was positive in lichen planus pemphigoides and negative in bullous lichen planus. Lichen planus pemphigoides and bullous lichen planus are separate entities: the former is an auto-immune disease precipitated by lichen planus and not related to bullous pemphigoid, the latter is probably not auto-immune but represents the extreme consequence of the lymphoid infiltrate at the dermo-epidermal junction.