Discuss the laboratory findings in patients with paraneoplastic pemphigus. Skin and oral mucous membrane biopsy specimens reveal epidermal acantholysis, epidermal spongiosis, suprabasilar clefts, basal cell vacuolar changes, and dyskeratotic keratinocytes. Direct immunofluorescent examination reveals IgG and, less commonly, IgA with or without complement in the intracellular spaces and C3, IgG, or IgM at the basement membrane zone. Antibodies have been demonstrated against desmoplakins, proteins in keratinocyte attachment plaques (desmosomes), and a 230-kDa protein in the basement membrane (bullous pemphigoid antigen). Rat bladder is a useful substrate for indirect immunofluorescent examination and shows positive staining with serum from patients with paraneoplastic pemphigus but will be negative with serum from patients with classic pemphigus vulgaris. Zhu X, Zhang B: Paraneoplastic pemphigus, J Dermatol 34:503–511, 2007. |
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