False-positive results with the radioactive phosphorus test

H. F. Shammas, T. C. Burton and T. A. Weingeist

A chorioretinal granuloma that contained acid-fast bacilli and a choriodal nevus that consisted of benign nevus cells yielded false-positive radioactive phosphorus tests. The beta emission exceeded that of the control areas by more than 100% in each case. The granuloma had infiltrated the sclera, permitting inflammatory tissue to be in closer proximity to the counting probe than was the normal choroid. The reason for the increased metabolic activity of the nevus cells remains unexplained.