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.

Primary lymphoma of the visual pathway is rare, especially at the chiasm. Very few cases have been reported. The lesion is frequently confused with an optic–hypothalamic glioma. A 55-year-old man was found disoriented at his home by a friend and evaluated with a brain MRI which demonstrated an expansile mass located at the optic chiasm and hypothalamus level. The principal differential was a high-grade hypothalamic glioma due to the contrast enhancement. A biopsy of the chiasmal lesion was performed. Histological diagnosis of the lesion was compatible with a diffuse large B cell lymphoma. He was started on methotrexate and rituximab; however, his clinical course kept deteriorating, and he died 64 days after his presentation. All prior cases of primary lymphoma of the chiasm are reviewed.