Bullous esophageal lesions due to cotrimoxazole: an immune-mediated process?

A 78-yr-old man experienced a generalized bullous eruption of the skin (a Stevens-Johnson variant of erythema multiforme) with simultaneous involvement of the esophagus due to co-trimoxazole. Immunologic tests revealed specific antibodies of the immunoglobulin G class but not of the immunoglobulin E class against sulfamethoxazole, and in particular against trimethoprim. Lymphocyte transformation tests demonstrated sensitized lymphocytes against trimethoprim but not sulfamethoxazole. The esophageal mucosa showed intraepithelial vesicle formation with diffuse cytoplasmic deposits of immunoglobulin G. This adverse drug reaction involving both the skin and the esophagus appears to be immune-mediated.