[A case of rheumatoid arthritis developing pemphigus-like skin lesion during treatment with bucillamine]

Bucillamine is a useful medication for treatment of rheumatoid arthritis (RA) but some patients develop side effects from it. Here, we report a patient with RA developing a pemphigus-like skin lesion during treatment with bucillamine. A 55 year old woman with RA (stage III, class II) had been treated with bucillamine in our hospital since September 1988. Her symptoms of RA had gradually improved after administration of bucillamine but the generalized skin rash with itching developed in June 1989. Skin biopsy revealed spongiosis, the infiltration of lymphocytes in the epidermis and inter-cellular deposition of IgG. These findings were consistent with the histological change of pemphigus. Since symptoms of the skin disappeared two months later after the discontinuation of bucillamine. We considered that her pemphigus-like lesion was induced by this drug. D-penicillamine is one of the drugs which induce pemphigus. Though the mechanisms of this side effect have not been clear, it is thought that autoantibody induced by D-penicillamine could be one of the cause of pemphigus. Because the chemical structure of bucillamine is similar to that of D-penicillamine, the autoimmune mechanisms may also play a role in the onset of the pemphigus-like lesion in this case.