Pembrolizumab for treatment of a male with primary mediastinal choriocarcinoma: a case report.

Background: Primary mediastinal choriocarcinoma is an extremely rare malignant tumor, that is prone to early metastasis and often misdiagnosed. Currently, there is no standardized treatment for primary mediastinal choriocarcinoma. Herein, we report a case to share our experience in the diagnosis and treatment of primary mediastinal choriocarcinoma. Case Description: A 19-year-old male patient who presented with chest pain and occasional cough for 1 month. He was diagnosed as mediastinal tumor with multiple lung metastases by imaging modalities in a local hospital, and therapeutic surgical excision was performed for the metastasis lesions in lower lobe of right lung. The pathological examination of the surgical specimens supported lung metastasis of choriocarcinoma. Then he was transferred to our hospital for further treatment. Elevated β-human chorionic gonadotropin (β-hCG) serum levels (>200,000 mIU/mL, normal <5 mIU/mL) combined with imaging modalities and pathological consultation of the surgical specimens at admission in our hospital supported the diagnosis of primary mediastinal choriocarcinoma with multiple metastases. During the treatment, we used a variety of treatments, including chemotherapy, radiotherapy and Pembrolizumab. After one cycle of EP chemotherapy (etoposide and cisplatin), computed tomography (CT) scan showed that new nodules appeared in the liver, mass in the anterior mediastinum and part of the nodules in the lungs were enlarged. Pembrolizumab was initiated because of the tumor cells were positive for programmed cell death 1 ligand 1 (PD-L1). The mediastinal mass shrank after two cycles of Pembrolizumab. However, due to the rapid progress of the disease, the patient died of the disease 4 months after the initial symptoms. Conclusions: Advanced primary mediastinal choriocarcinoma is highly aggressive and insensitive to chemotherapy. Pembrolizumab may be used as a salvage treatment for primary mediastinal choriocarcinoma.