Drug-triggered pemphigus in a predisposed woman

A 31-year-old woman with three pemphigus-prone antigens in her HLA haplotype (B7, DR4, DQw7) developed the disease soon after taking a pyrazolone derivative, viz. feprazone. The pemphigus lesions persisted despite withdrawal of the drug and worsened appreciably when she used ceftriaxone (a new cephalosporin with three sulphur atoms) for a bout of acute pharyngitis. Thiol groups formed from the metabolic breakdown of ceftriaxone are thought to have promoted acantholysis via a biochemical route. Genetic predisposition alone ('the soil') may be essential, though not per se sufficient for outbreak of pemphigus; the intervention of exogenous, heterogeneous factors ('the seed') often seems decisive in triggering full-blown disease.