Heterophile Antibody Interference led to Unneeded Chemotherapy in a Testicular Cancer Patient.

Human heterophile antibodies may develop after infection or contact with animal tissues or animal serum products. These antibodies have the capacity to bind to the animal immunoglobulins used in immunoassays leading to erroneous results. We here report a case of a testicular germ cell tumor patient who developed heterophile antibodies during the surveillance period of his disease. Following false-positive results of human chorionic gonadotropin (hCG) he received unneeded chemotherapy. This article also stresses the problem of using serum tumor markers without no major imaging abnormalities to diagnose a patients' relapse.