Postherpetic Oral Ulcers Misdiagnosed as Pemphigus in a Patient with Rheumatoid Arthritis under Bucillamine Therapy

Autoimmune bullous disease is sometimes seen in patients with rheumatoid arthritis (RA). In addition, pemphigus can be induced by certain disease modifying anti-rheumatic drugs (DMARDs) for RA, such as thiol compounds. Antibodies against desmogleins are occasionally detected in the sera of drug-induced pemphigus patients. We herein describe a case which showed ulceration following herpes zoster in the oral cavity of a patient with RA under treatment with bucillamine. The patient was misdiagnosed with pemphigus in another clinic, because of mucous membrane lesions and positive circulating levels of anti-desmoglein-1 IgG. Clinicians should know that circulating antibodies against desmogleins can be detected, although at low titers, in the sera of patients under therapies with certain drugs.