Beta-Human Chorionic Gonadotropin Expression in Recurrent and Metastatic Giant Cell Tumors of Bone

Giant cell tumors of bone (GCTs) are generally benign, locally aggressive neoplasms that rarely metastasize. The beta subunit of human chorionic gonadotropin (beta-hCG) is expressed in syncytiotrophoblasts and several nongynecologic neoplasms but has not been described in GCT. At our institution, we observed cases of elevated beta-hCG in patients with GCT leading to diagnostic difficulty and in one case, concern for metastatic choriocarcinoma. This study aims to determine the frequency of beta-hCG expression in GCT and any relationship to clinical aggressiveness. We evaluated tissue expression of beta-hCG by immunohistochemistry with 58% of cases staining for beta-hCG. Additionally, 2 of 11 patients with available serum and/or urine beta-hCG measurements demonstrated elevated beta-hCG due to tumor. It is important to be aware of beta-hCG expression by GCT and the potential for elevated urine and serum beta-hCG levels in patients with GCT so as to avoid misdiagnosis of pregnancy or gestational trophoblastic disease.