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Chapter 055. Immunologically Mediated Skin Diseases (Part 3)

Pemphigus Foliaceus Pemphigus foliaceus (PF) is distinguished from PV by several features. In PF, acantholytic blisters are located high within the epidermis, usually just beneath the stratum corneum. Hence PF is a more superficial blistering disease than PV. The distribution of lesions in the two disorders is much the same, except that in PF mucous membranes are almost always spared. Patients with PF rarely demonstrate intact blisters but rather exhibit shallow erosions associated with erythema, scale, and crust formation. Mild cases of PF resemble severe seborrheic dermatitis; severe PF may cause extensive exfoliation. Sun exposure (ultraviolet irradiation) may be. | Chapter 055. Immunologically Mediated Skin Diseases Part 3 Pemphigus Foliaceus Pemphigus foliaceus PF is distinguished from PV by several features. In PF acantholytic blisters are located high within the epidermis usually just beneath the stratum corneum. Hence PF is a more superficial blistering disease than PV. The distribution of lesions in the two disorders is much the same except that in PF mucous membranes are almost always spared. Patients with PF rarely demonstrate intact blisters but rather exhibit shallow erosions associated with erythema scale and crust formation. Mild cases of PF resemble severe seborrheic dermatitis severe PF may cause extensive exfoliation. Sun exposure ultraviolet irradiation may be an aggravating factor. Fogo selvagem FS an endemic form of PF thought to develop as a consequence of environmental stimuli e.g. insect bites is found in south central rural Brazil as well as selected sites in Latin America and Tunisia. Patients with PF have immunopathologic features in common with PV. Specifically direct immunofluorescence microscopy of perilesional skin demonstrates IgG on the surface of keratinocytes. Similarly patients with PF have circulating IgG autoantibodies directed against the surface of keratinocytes. Guinea pig esophagus is the optimal substrate for indirect immunofluorescence microscopy studies of sera from patients with PF. In PF autoantibodies are directed against Dsg1 a 160-kDa desmosomal cadherin. As noted for PV the autoantibody profile in patients with PF i.e. anti-Dsg1 IgG and the tissue distribution of this autoantigen i.e. expression in oral mucosa that is compensated by coexpression of Dsg3 is thought to account for the distribution of lesions in this disease. Although pemphigus has been associated with several autoimmune diseases its association with thymoma and or myasthenia gravis is particularly notable. To date 30 cases of thymoma and or myasthenia gravis have been reported in association with pemphigus usually