They are postulated to release proteolytic enzymes which degrade the hemidesmosomal proteins, resulting in blister formation.Other potential contributory factors including genetic factors, environmental exposures to infections and drugs as well as the phenomenon of epitope spreading are also known to cause bullous pemphigoid. Diagnosis
Diagnosis of bullous pemphigoid includes clinical assessment, skin biopsy for histopathology and direct immunofluorescence, indirect immunofluorescence and ELISA test. Among all, direct immunofluorescence is the gold standard for diagnosis of bullous pemphigoid. Clinical assessment
For patients greater than 70 years old 
Blistering skin disease characterized by the presence of tense blisters and erosions that occur without another identifiable cause and rarely on mucosa. Unexplained pruritus, pruritic eczematous eruptions, or urticarial plaques

Histopathology
Lesional tissue, preferably of an intact vesicle or the edge of an intact bulla is obtained using punch biopsy for Haemotoxylin and Eosin (H&E)staining. Typical histopathologic findings include:
Sub-epidermal split with numerous eosinophils within the cleft. A superficial dermal inflammatory cell infiltrate of variable intensity with lymphocytes, eosinophils, and neutrophils. Eosinophlic spongiosis (Specifically in early lesion or may be seen in clinically erythematous skin surrounding the blister)

Direct immunofluorescence
Direct immunofluorescence (DIF) studies involves directly detecting tissue bound antibodies. Biopsy specimens for DIF should be taken from perilesional skin instead of lesional skin for H&E histopathologic evaluation. DIF specimens should be placed in Michels solution or Zeuss transport media instead of formalin. DIF of bullous pemphigoid will show the presence of fine, continuous and linear deposits of IgG and/or C3 along the epidermal basement membrane.
Necrolytic acral erythema is a cutaneous condition that is a manifestation of hepatitis C viral infection or zinc deficiency.It is a papulosquamous and sometimes vesiculobullous eruption bearing clinical and histologic similarity to other necrolytic erythemas such as necrolytic migratory erythema, pseudoglucagonoma and nutritional deficiency syndromes. See also
List of cutaneous conditions

References


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