Pemphigus Foliaceus and Pemphigus Erythematosus
Pemphigus foliaceus (PF) has several subsets including an endemic form (fogo selvagem) and pemphigus erythematosus (PE, also known as Senear-Usher Syndrome). All have similar clinical and immunopathologic features. Idiopathic PF and PE are rare disorders seen predominantly in the elderly. Men and women are affected equally. The endemic form of PF is seen in rural areas of Brazil and typically occurs in children and in young adults without any racial or ethnic predilection.
Clinically, the primary lesion common to all is a superficial, flaccid, vesiculopustule, which ruptures, leading to the formation of scaly, crusted erosions. Lesions are typically painful and patients often describe a burning sensation. In PF and endemic PF, disease may be localized to seborrheic areas such as the face, scalp or upper trunk or it may generalize resulting in an exfoliative erythroderma. PE is the localized form of PF and represents a clinical overlap between PF and cutaneous lupus. Patients present with red, scaly, crusted lesions usually limited to the upper back, neck and head. Facial plaques may have a malar distribution similar to systemic lupus erythematosus. This form may generalize into a picture indistinguishable from that of PF. In all types, mucosal surfaces are not affected and exposure to sun and/or heat may exacerbate symptoms.
PF, endemic PF, and PE are intraepidermal autoimmune blistering disorders that occur secondary to the formation of antibodies that interact with desmoglein 1. This is a 160 kDa transmembrane glycoprotein of the desmosomal junction. Light microscopy demonstrates subcorneal bullae with acantholysis in the granular layer. Subcorneal pustules with neutrophils may also be seen.
As with pemphigus vulgaris, the hallmark of PF is the finding of IgG autoantibodies in the epidermis. PF cannot be differentiated from pemphigus vulgaris by the immunofluorescent pattern alone. Direct immunofluorescence of perilesional skin is positive for intercellular IgG in virtually all patients with active PF/PE. In addition, patients with PE typically demonstrate C3 in the epidermal intercellular spaces and at the basement membrane zone of erythematous facial skin. Indirect immunofluorescence is positive in the majority of patients and titers tend to correlate well, although imprecisely, with disease activity. Many patients with PE will also have positive antinuclear antibodies on serologic exam.
In general, PF and PE have a better prognosis than pemphigus vulgaris. However, prior to the advent of glucocorticoid therapy, the mortality rate was as high as 60%.