Harrison's Internal Medicine Chapter 55. Immunologically Mediated Skin Diseases Immunologically Mediated Skin Diseases: Introduction A number of immunologically mediated skin diseases and immunologically mediated systemic disorders with cutaneous manifestations are now recognized as distinct entities with consistent clinical, histologic, and immunopathologic findings. Many of these disorders are due to autoimmune mechanisms. Clinically, they are characterized by morbidity (pain, pruritus, disfigurement) and in some instances by mortality (largely due to loss of epidermal barrier function and/or secondary infection). . | Chapter 055. Immunologically Mediated Skin Diseases Part 1 Harrison s Internal Medicine Chapter 55. Immunologically Mediated Skin Diseases Immunologically Mediated Skin Diseases Introduction A number of immunologically mediated skin diseases and immunologically mediated systemic disorders with cutaneous manifestations are now recognized as distinct entities with consistent clinical histologic and immunopathologic findings. Many of these disorders are due to autoimmune mechanisms. Clinically they are characterized by morbidity pain pruritus disfigurement and in some instances by mortality largely due to loss of epidermal barrier function and or secondary infection . The major features of the more common immunologically mediated skin diseases are summarized in this chapter Table 55-1 as are the systemic disorders with cutaneous manifestations. Table 55-1 Immunologically Mediated Blistering Diseases Disease Clini cal Histolo gy Immunopat hology Autoanti gens Pemphig us foliaceus Crust s and shallow erosions on scalp central face upper chest and back Acantho lytic blister formed in superficial layer of epidermis Cell surface deposits of IgG on keratinocytes Dsg1 Pemphig us vulgaris Flacci d blisters denuded skin oromucosal Acantho lytic blister formed in suprabasal layer of Cell surface deposits of IgG on keratinocytes Dsg3 plus Dsg1 in patients with skin lesions epidermis involvement Paraneo plastic pemphigus Painf ul stomatitis with papulosqua mous or lichenoid eruptions that progress to blisters Acantho lysis keratinocyte necrosis and vacuolar interface dermatitis Cell surface deposits of IgG and C3 on keratinocytes and variably similar immunoreactants in epidermal BMZ Plakin protein family members and desmosomal cadherins see text for details Bullous pemphigoid Large tense blisters on flexor surfaces and trunk Subepid ermal blister with eosinophil-rich infiltrate Linear band of IgG and or C3 in epidermal BMZ BPAG1 BPAG2 Pemphig oid gestationis Prurit ic urticarial
