A PSEUDOEPIDEMIC OF TUBERCULIN SKIN TEST CONVERSIONS CAUSED BY A PARTICULAR LOT OF PURIFIED PROTEIN DERIVATIVE OF TUBERCULIN TEST SOLUTION

The Mantoux test, involving the intracutaneous injection of purified protein derivative of tuberculin (PPD), constitutes the standard method for the diagnosis of tuberculosis. False negative reactions to the Mantoux test are noted rather frequently, but false positive reactions are less commonly reported. We describe a cluster of 11 cases of false positive PPD reactions occurring during a 1-month period in a pediatric clinic; such reactions were characterized by an immediate wheal and flare reaction, excessive erythema and pruritus and unusual scarring.