A complicated blistering disease case demonstrating the usefulness of immunoblotting and ELISA for the diagnosis of immunobullous diseases

Abstract

A 51 year old female was referred for evaluation of a transient pruritic blistering eruption located on the trunk and extremities. She had a complicated medical background including rheumatoid arthritis and drug‐induced lupus erythematosus from the TNF blocker adalimubab. Her medications included prednisone 4 mg/day and hydroxychloroquine 400 mg/day. On examination a few large tense blisters were noted and the Nikolsky sign was negative.A routine skin biopsy showed intraepidermal vesicles, eosinophilic spongiosis and significant subepidermal oedema, but no acantholysis. Direct immunofluorescence (DIF) showed IgG depositions in an intercellular pattern in the upper epidermis, and IgM depositions in a granular pattern at the dermo‐epidermal junction. Indirect immunofluorescence on monkey oesophagus and rat bladder was negative, whereas salt‐split skin showed positive staining for IgG in the roof of the blister.As it was difficult to establish a unifying diagnosis given these clinical and histopathological features, the auto‐antigenic targets were studied by ELISA and immunoblotting techniques. ELISA showed IgG reactivity to the 165 kd desmoglein 1 antigen, but not to desmoglein 3. Immunoblotting to basement membrane components was negative. These results supported a unifying final diagnosis of pemphigus foliaceus. She has been treated with minomycin and topical corticosteroids and has had a benign course.This case demonstrates the concurrence of multiple serious autoimmune diseases, which represent an ongoing diagnostic and management challenge. Although the molecular pathogenesis of autoimmune blistering diseases is well understood, clinico‐pathological correlation may not always be achieved with routine dermatohistopathology and immunofluorescence examination. This case demonstrates the utility of additional molecular techniques in differentiating blistering diseases, which has important implications for management and prognosis.