Subcorneal pustular dermatosis-type IgA pemphigus induced by thiol drugs

We report a case of subcorneal pustular dermatosis (SPD)-type IgA pemphigus arising in a 49 year-old woman with rheumatoid arthritis who had been trea ted with chrysotherapy. Scaly erythemic plaques containing vesicles and pus tules occurred on her chest and abdomen during the course of anti-rheumatic treatments using prednisolone at 11 mg/day and thiol compounds (bucillamin e and gold sodium thiomalate). Histological investigations revealed subcorn eal pustules containing many neutrophils and a few acantholytic cells, and intercellular IgA deposits at the upper epidermis of the eruptions without any other immunoglobulins and complement component C3. Circulating IgA anti bodies directed against intercellular spaces of the epidermis were found by prolonged incubation of normal skin specimens in medium containing 20% pat ient's serum in an explant culture, although standard indirect immunofluore scence for IgA antibodies was negative. The eruptions were treated successf ully with prednisolone, 30 mg/day, dapsone, 50 mg/day, and discontinuance o f the thiol compound. In addition to the coexistent rheumatoid arthritis, b oth thiol compounds might have been responsible for the development of the eruptions.