Lichen planus pemphigoides is characterized by the development of tense blisters atop lesions of lichen planus

Lichen planus

Lichen planus is a chronic mucocutaneous disease that affects the skin, tongue, and oral mucosa. The disease presents itself in the form of papules, lesions, or rashes. Lichen planus does not involve lichens, the fungus/algae symbionts that often grow on tree trunks; the name refers to the dry and...

 or the development vesicles de novo on uninvolved skin. It is important to differentiate this entity from bullous lichen planus

Bullous lichen planus

Bullous lichen planus is a rare variant of lichen planus, characterized by the development of vesicles and bullae with the skin lesions....

, in which blisters develop in skin lesions of longstanding lichen planus as a result of intense lichenoid inflammation and extensive liquefaction degeneration of basal keratinocytes.