Lymphomatosis cerebri with cauda equina lymphoma.

Lymphomatosis cerebri (LC) and cauda equina lymphoma are both rare forms of primary central nervous system lymphoma (PCNSL). LC is characterized by diffuse bilateral non-enhancing (or partially enhancing) infiltrative lesions without mass effect, which can be easily confused with other forms of leukoencephalopathy and, thus, lead to delays in diagnosis. For the first time, a case of LC concomitant with cauda equina involvement confirmed by brain stereotactic biopsy is presented. This case highlights the necessity of using a multimodal strategy in diagnosing PCNSL, including multimodal magnetic resonance, cerebral spinal fluid cytology, flow cytometry and fluorodeoxyglucose positron emission tomography/computed tomography.