Unusual cauda equina syndrome due to multifocal ependymoma infiltrated by lymphoma.

Myxopapillary ependymoma is a rare tumour of the central nervous system (CNS); this subtype of ependymoma occurs most frequently in cauda equina, conus medullaris or filum terminale. The treatment consists of complete removal of the tumour including its capsule when possible since it is usually a solitary lesion. Non-Hodgkin lymphoma of the CNS is found in only 1.3% of cauda equina tumours. We report the case of a 62-year-old man who presented to our institution with progressive weakness of his right lower extremity, with numbness and paresthesia of both feet. He was suffering from one month of right sciatica. Lumbosacral MRI displayed two intradural extramedullary lesions, the first one was located posteriorly to L1-L2 and the second one was spreading from L4 to S2 presenting as a mucoid cyst in its superior part with hyperintense T2 signal, isointense on T1-weighted with high and homogeneous contrast enhancement in the inferior solid component. Imaging also found three additional intradural, extramedullary tumor formations with contrast enhancement, located respectively at C5-C6, C7 and T4. A L1-L2 and S1-S2 laminectomy was performed in emergency and total removal was achieved. Neuropathologist concluded that the tumor was a myxopapillary ependymoma infiltrated by large B-cell lymphoma. Although rare, this phenomenon (coexisting tumors within the same lesion) should be known by neurosurgeons because the occurrence of collision tumors affects the treatment and the patient's prognosis. In our case, two different types of tissue were mingled in the same location-this finding is very uncommon and has, to our knowledge, never been reported before.