False positive beta-human chorionic gonadotropin in testicular cancer.

Persistent elevations in serum markers after chemotherapy for germ cell testicular carcinoma indicate residual disease. We report on a patient with advanced seminoma with choriocarcinoma who had elevated serum beta-human chorionic gonadotropin (beta-HCG) and residual masses on computerized tomography scan after chemotherapy. Wedge liver resection and retroperitoneal node dissection yielded only necrotic tissue which assayed and immunoperoxidase stained positively for beta-HCG. Serum beta-HCG fell to undetectable levels postoperatively, and the patient remains disease-free after three years. Phagocytosis of necrotic tumor apparently released entrapped beta-HCG resulting in a false positive tumor marker.