ERUPTIONS of lichen planus associated with vesicles, although not common, are not a great rarity. The vesicles may be few and scattered and of small size, or there may be multiple crops of vesicles and even large bullae. Reports of this form of eruption have appeared in the literature since 1881 when Baker (Crocker1) was credited as having first described such a complication of lichen planus. Kaposi2has been generally credited with the origin of the term lichen ruber pemphigoides and with the first description of an extensive bullous eruption occurring in lichen planus. Kaposi stated that while he had seen lichen planus associated with pea-sized vesicles, he had never previously seen large bullae in lichen planus. He apparently coined the term lichen ruber pemphigoides to segregate this eruption of bullous lichen planus from the commoner vesicular lichen planus. The term lichen ruber pemphigoides, or lichen planus pemphigoides,