Choriocarcinoma is a highly malignant tumour emerging from the syncytiotrophoblast divided into gestational and non-gestational presentations. Primary choriocarcinoma of the mediastinum is rare. Metastases to the brain often occur; however, brainstem involvement has not been reported for non-gestational choriocarcinoma. We described a middle-aged man who developed a complete left oculomotor nerve paralysis secondary to a brainstem tumour at the midbrain. The workup for the primary source of the brainstem tumour included a chest CT scan, which revealed a mediastinal mass. A mediastinal mass needle biopsy confirmed the diagnosis of primary mediastinal choriocarcinoma. Despite aggressive chemotherapy, the patient died 6 months after the initial presentation from neurological complications and multiorgan failure.
