Supratentorial malignant lymphoma presenting with peduncular hallucination.

A 44-year-old man suffered headache and sleep disturbance for 2 weeks. At the presentation, the patient confessed visual hallucinations for 1 week. Cerebral magnetic resonance imaging (MRI) revealed an enhancing mass in the right frontal lobe, accompanied by considerable midline shift and midbrain deformation. During hospitalization, the patient frequently experienced vivid visual hallucinations. They were perceived as being alone or many strangers standing at the bedside or entrance of the room, or a stranger sleeping next to him lying on the bed. The patient underwent partial tumor resection that led to the diagnosis of diffuse large B-cell lymphoma. Subsequently, he underwent 6 courses of chemotherapy. The patient's hallucinations resolved 3 weeks after induction of chemotherapy. MRI at the completion of chemotherapy revealed a remarkable regression of the tumor with restoration of midbrain contour. In this case, the frontal tumor was assumed to cause peduncular hallucinations. Supratentorial massive lymphomas can cause peduncular hallucinations that are effectively managed by chemotherapy.