Primary retroperitoneal choriocarcinoma with lung and liver metastasis in a male patient: case report

Objectives Non-gestational primary choriocarcinoma is an extremely rare malignant tumor with atypical clinical symptoms, especially in males. It usually occurs in the midline of the body, such as the mediastinum and retroperitoneum. Pathological diagnosis of primary retroperitoneal choriocarcinoma presents many challenges. More importantly, it is insensitive to therapy and has a poor prognosis. To date, there is still no standard treatment strategy for primary choriocarcinoma.Case presentation This case report presented a 27-year-old male with acute abdominal pain as the main symptom. And then, retroperitoneal choriocarcinoma with lung and liver metastasis was diagnosed. Palliative surgery was performed to alleviate the abdominal pain but complete tumor removal was not achieved. Subsequently, we gave the treatment with cytotoxic chemotherapy and immune checkpoint inhibitor blockade. The tumor was significantly reduced in size after six cycles of immunotherapy and chemotherapy, and also beta-hCG level returned to normal. The tumor was not in complete remission, so penpulimab immuno-maintenance therapy was given. So far, the tumor control is stable, and the patient's quality of life is also very well.Conclusions Pathological diagnosis of primary choriocarcinoma is very necessary, and the related molecular markers can assist. Immunotherapy combined with chemotherapy is effective in the treatment of primary retroperitoneal choriocarcinoma.