Tislelizumab for treatment of a pediatric patient with primary mediastinal choriocarcinoma: a case report.

Background: Primary mediastinal choriocarcinoma (PCC) is a rare, highly vascular invasive, and prognostically unfavorable malignant tumor. When occurring outside the gonads, primary choriocarcinoma is commonly found in midline locations such as the mediastinum or retroperitoneum. Currently, there is no standardized treatment strategy for PCC. In the case reported herein, we employed tislelizumab and chemotherapy in the treatment of a patient with PCC, and as in March 2024, the patient remained survive.

Case description: A 15-year-old boy who presented with symptoms of fever and cough for a year. Chest computed tomography (CT) scan showed a relatively large soft tissue shadow in the right upper anterior mediastinum, measuring approximately 5.4 cm × 3.8 cm. The patient's soft tissue exhibited unclear demarcation from surrounding mediastinal structures and was accompanied by lung metastasis. The patient underwent a fine needle aspiration biopsy for a mediastinal mass, and the pathology results indicated a germ cell tumor with solid malignant components in the mediastinum, along with pulmonary metastasis of the solid malignancy. The patient's serum levels of beta-human chorionic gonadotropin (β-HCG) were elevated at 125,554 mIU/mL (normal range: <5 mIU/mL), and alpha-fetoprotein (AFP) was 75.8 ng/mL (normal range, 0.605-7 ng/mL). The patient's cranial magnetic resonance imaging (MRI) plain scan indicated multiple scattered abnormal signals in both cerebral hemispheres. Subsequently, the patient was transferred to Children's Hospital of Nanjing Medical University for his further treatment. During the treatment period, we employed various therapeutic approaches, including chemotherapy, radiotherapy and tislelizumab therapy. After five cycles of tislelizumab treatment, the patient's symptoms of cerebral edema significantly improved, β-HCG levels decreased. Brain MRI of the patient revealed multiple abnormal signals within the skull, with some lesions showing reduction in size and significant improvement in the surrounding edema zones. The clinical symptoms of the patient improved and he achieved partial remission (PR). At the moment, the patient is living with the disease.

Conclusions: The effectiveness of chemotherapy for PCC is limited. Tislelizumab may potentially serve as salvage treatment options for PCC.