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Bullous diseases are defined as conditions where cavities filled with fluid form in the superficial layers of the skin clinically manifesting as vesicles or blisters. Although vesicles and blisters can arise as secondary lesions in many conditions, in the bullous diseases they are the primary pathologic event. Genetic (hereditary) and acquired (mostly autoimmune) bullous diseases exist.
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HEREDITARY EPIDERMOLYSIS BULLOSA (EB) ICD-10: Q 81
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A spectrum of rare genodermatoses in which a disturbed coherence of the epidermis and/or dermis leads to blister formation following trauma. Hence, the designation mechanobullous dermatoses.
Disease manifestations range from very mild to severely mutilating and even lethal forms that differ in modes of inheritance, clinical manifestations, and associated findings.
Classification based on the site of blister formation distinguishes three main groups: epidermolytic or epidermolysis bullosa (EB) simplex, junctional EB (JEB), and dermolytic or dystrophic EB (DEB).
In each of these groups, there are several distinct types of EB based on clinical, genetic, histologic, and biochemical evaluation.
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Based on the level of cleavage and blister formation, there are three main types:
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Epidermolytic. Cleavage occurs in keratinocytes: epidermolysis bullosa (EB) simplex (EBS).
Junctional. Cleavage occurs in basal lamina: junctional EB (JEB).
Dermolytic. Cleavage occurs in most superficial papillary dermis: dermolytic or dystrophic EB (DEB).
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In each of these groups, there are several distinct types of EB based on clinical, genetic, histologic/electron microscopic, and biochemical evaluation (Table 6-1). Only the most important are discussed here.
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