False-positive β-human chorionic gonadotropin values in the follow-up of gestational trophoblastic disease

Gestational trophoblastic disease consists of a pathological spectrum of entities from molar pregnancies, which are premalignant conditions, to malignant invasive choriocarcinoma. Serum β-human chorionic gonadotropin (hCG) levels are essential both in the diagnosis and in the follow-up. There are high rates of complete responses and long-term survivors, because of the excellent chemosensitivity of these tumours. After initial management, an increased level of β-hCG indicates persistent disease. However, in the absence of evidence of persistent disease, false-positive β-hCG values may be considered. We present here the case of a woman with a metastatic choriocarcinoma in complete response after chemotherapy, who developed later persistent false-positive values of β-hCG in the follow-up. Causes of false-positive β-hCG determinations are revised.