Chapter 055. Immunologically Mediated Skin Diseases (Part 1)

Harrisons Internal Medicine Chapter 55. Immunologically Mediated Skin DiseasesImmunologically Mediated Skin Diseases: IntroductionA 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). ...
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Chapter 055. Immunologically Mediated Skin Diseases (Part 1) Chapter 055. Immunologically Mediated Skin Diseases (Part 1) Harrisons Internal Medicine > Chapter 55. Immunologically MediatedSkin Diseases Immunologically Mediated Skin Diseases: Introduction A number of immunologically mediated skin diseases and immunologicallymediated systemic disorders with cutaneous manifestations are now recognized asdistinct entities with consistent clinical, histologic, and immunopathologicfindings. Many of these disorders are due to autoimmune mechanisms. Clinically,they are characterized by morbidity (pain, pruritus, disfigurement) and in someinstances by mortality (largely due to loss of epidermal barrier function and/orsecondary infection). The major features of the more common immunologicallymediated skin diseases are summarized in this chapter (Table 55-1), as are thesystemic disorders with cutaneous manifestations. Table 55-1 Immunologically Mediated Blistering Diseases Disease Clini Histolo Immunopat Autoanti cal gy hology gensa Pemphig Crust Acantho Cell surface Dsg1us foliaceus s and lytic blister deposits of IgG on shallow formed in keratinocytes erosions on superficial scalp, layer of central face, epidermis upper chest, and back Pemphig Flacci Acantho Cell surface Dsg3us vulgaris d blisters, lytic blister deposits of IgG on (plus Dsg1 in denuded formed in keratinocytes patients with skin, suprabasal skin oromucosal layer of lesions epidermis involvement) Paraneo Painf Acantho Cell surface Plakinplastic ul stomatitis lysis, deposits of IgG and protein familypemphigus with keratinocyte C3 on keratinocytes members and papulosqua necrosis and and (variably) desmosomal mous or vacuolar similar cadherins (see lichenoid interface immunoreactants in text for details) eruptions dermatitis epidermal BMZ that progress to blisters Bullous Large Subepid Linear band BPAG1,pemphigoid tense blisters ermal blister of IgG and/or C3 in BPAG2 on flexor with epidermal BMZ surfaces and eosinophil-rich trunk infiltrate Pemphig Prurit Teardro Linear band BPAG2oid gestationis ic, urticarial p-shaped, of C3 in epidermal (plus BPAG1 in plaques, subepidermal BMZ some patients) rimmed by blisters in vesicles and dermal bullae on the papillae; trunk and eosinophil-rich extremities infiltrate Linear Prurit Subepid Linear band BPAG2IgA disease ic small ermal blister of IgA in epidermal (see text for papules on with BMZ specific details) extensor neutrophil-rich surfaces; infiltrate occasionally larger, arciform blisters Cicatrici Erosi Subepid Linear band BPAG2,al pemphigoid ve and/or ermal blister of IgG, IgA, and/or laminin 5, or blistering that may or C3 in epidermal others lesions of may not BMZ mucous include a membranes leukocytic and possibly infiltrate the skin; scarring of some sites Epiderm ...