Pure testicular choriocarcinoma, a rare and highly malignant subtype with challenging treatment: A case report and review of the literature.

Testicular choriocarcinoma (CC) is the rarest subtype of germ cell tumours (GCTs) of the testis, with a high malignant potential and early haematogenous metastasis. Radical surgical resection should be performed primarily for histological diagnosis, while chemotherapy remains the mainstay of therapy for advanced disease. In the present study, the case of a 65-year-old male patient diagnosed with metastatic testicular CC, who did not fully respond to chemotherapy is reported. This patient underwent surgical removal of the testicular tumour, chemotherapy with etoposide and cisplatin, and radiotherapy of the intracranial lesions. Although the serum human chorionic gonadotropin (HCG) levels of the patient and most of the metastases continued decreasing during chemotherapy, complete response was not achieved after six cycles of chemotherapy. The patient refused high-dose chemotherapy and autologous stem cell transplantation due to severe side effects, and eventually developed respiratory failure on maintenance therapy with oral etoposide. A literature review was then performed, aiming to summarize the characteristics and therapeutic principles of testicular CC. In addition, the emerging therapeutic agents that could be used in maintenance therapy for GCTs, particularly for testicular CC, were also discussed. The limited clinical trials of targeted treatments showed potential benefit for long survival of patients with selected GCTs with fewer side effects. In particular, immunotherapy showed unique potential for testicular CC in preclinical studies, offering new approaches of maintenance therapy for advanced disease. Further studies should shed light on the identification of prognostic factors that predict the response to immune-based therapy in GCTs.