A possible case of drug-induced familial pemphigus

Two sisters developed pemphigus vulgaris and pemphigus erythematosus within 3 years. The diagnosis was confirmed by clinical, histologic and immunofluorescent antibody studies. One of the sisters experienced a common cold before the pemphigus developed and displayed a positive macrophage migration inhibition (MIF) test to a combination drug compounded of paracetamol, caffeine, chlorpheniramine maleate and phenylephrine HCl, which she had received 2 weeks prior to the appearance of the cutaneous lesions. It is suggested that her pemphigus was triggered by the drug. Although the patient had a strong genetic and familial predisposition to pemphigus, her clinical symptoms did not become evident until they were activated through an exogenous factor, namely, the causative drug. This case offers an example of a possible interaction between endogenous, genetic factors, and exogenous, triggering factors in the development of full-blown disease.