Pemphigus is a blistering disease of the skin and mucous membranes. There are at least two major variants: pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Most patients are between the ages of 40 and 60. Patients with PV often present with painful oral ulcers (Fig. 30-1). The mouth sores or desquamative gingivitis are followed by skin lesions including flaccid bullae, which may be so fragile that they are sometimes not observed, and only erosions and crusts are seen (Fig. 30-2). Oral PV can develop by itself in the absence of skin disease. In contrast, the lesions of PF are superficial, are localized to the head, neck, and upper trunk, and rarely involve the mouth.