Pemphigus vulgaris (PV) is the most common form of pemphigus in North America and Europe. The mean age of onset is 50 to 60 years of age and it affects both sexes equally. It is more common in Jews and in people of Mediterranean descent.
Clinically, mucous membranes are always involved. Patients typically present with painful oral mucous membrane erosions although other mucous membranes such as the pharynx, larynx, esophagus, conjunctiva, anus, penis, vagina, and labia may be involved. Cutaneous involvement is variable. The primary lesion is a non-inflamed, flaccid bullae. However, intact bullae are found infrequently because the vesicle roof consists of only a thin portion of epidermis that breaks easily. Therefore, the most common mucocutaneous lesions are erosions subsequent to ruptured bullae. These lesions are typically painful, not pruritic and they are often large, due to their tendency to spread peripherally. Lesions are positive for Nikolsky’s sign (lateral pressure of unblistered skin at the periphery of active lesions causes the epidermis to shear off) and for Asboe Hansen’s sign (pressure to the top of a bullae causes extension of the blister to adjacent unblistered skin).
PV is an intraepidermal autoimmune blistering disorder that occurs secondary to the formation of antibodies that interact with desmoglein 3. This is a 130 kDa transmembrane glycoprotein of the desmosomal junction. Binding of IgG autoantibodies to desmoglein 3 causes acantholysis by interfering with the adhesion of adjacent desmogleins, without the participation of other inflammatory events. Histopathologic exam demonstrates suprabasilar bullae with acantholysis. The basal cells remain fixed to the basement membrane but may lose contact with adjacent cells thus giving the appearance of a row of tombstones. The upper epidermal cells usually remain intact.
The hallmark of PV is the finding of IgG autoantibodies in the epidermis. Direct immunofluorescence of perilesional skin is positive for intercellular IgG in virtually all patients with active PV. Indirect immunofluorescence is positive in about 75% of patients and titers tend to correlate well, although imprecisely, with disease activity. Therefore, it is more important to follow clinical disease activity than antibody titers in the daily management of patients.