Thiopronine-induced herpetiform pemphigus: report of a case studied by immunoelectron microscopy and immunoblot analysis.

We report a case of herpetiform pemphigus induced by thiopronine. Direct immunoelectron microscopy performed on peribullous skin showed IgG deposits predominantly located in the extracellular portion of desmosomes. By immunoblot analysis using bovine tongue extracts as the antigen, the patient's serum recognized a 160-kDa polypeptide which comigrated with desmoglein I. This study underlines the contribution of immunoblot analysis to the diagnosis of atypical cases of pemphigus, and confirms that herpetiform pemphigus may be a clinical variant of pemphigus foliaceus.