Anti-desmoplakin (DP) I and II are detected in patients with paraneoplastic pemphigus. However, these autoantibodies have also been detected in patients with other disorders. A 73-year-old woman presented with a 20-year history of erosions and ulcers of the tongue and oral mucosa. Biopsy specimens of the oral mucosa showed several necrotic keratinocytes in the mucosal epithelium. The patient's serum was negative for anti-desmoglein 1 and anti-desmoglein 3 antibodies by ELISA, although anti-keratinocyte cell surface antibodies were detected by indirect immunofluorescence. On immunoblotting using protein extracts of normal human epidermis, the patient's serum was found to contain autoantibodies to 250 kDa and 210 kDa proteins, indicating the presence of autoantibodies to DP I and II. Based on these results, the diagnosis of erythema multiforme was made. An immunofluorescence and immunoblotting are crucial for the differential diagnosis between an erythema multiforme which is positive for anti-DP I and II antibodies and other autoimmune bullous diseases.
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