Spinal cauda equina lymphoma (CEL) is very rare, with only about 14 cases reported in the English medical literature. Magnetic resonance image findings and the gross appearance of CEL at surgery are similar to those of non-neoplastic hypertrophic neuropathy of the cauda equina (HNCE); however, their prognosis and treatment are very different.

Shin et al. report a case of CEL and discuss the differences from non-neoplastic HNCE ¹⁾.

Nakashima et al. report an extremely rare primary lymphoma in the cauda equina in a single case with literature review. An immunocompetent 59-year-old male, who complained of progressive low back and bilateral leg pain for 7 months, was studied. Magnetic resonance imaging (MRI) revealed an intradural space-occupying lesion from T12 to S1, poorly demarcated to the normal cauda equina. The intradural lesion showed T1 low intensity, T2 low isointensity, and marked homogeneous enhancement with gadolinium-diethylenetriaminepentaacetic acid on MRI. We performed spinal tap to obtain additional information about the intradural lesion. Large-sized atypical lymphoid cells were found during pathological examination. Fluorodeoxyglucose accumulation was found only in the lumbar area, which corresponded with the MRI findings, and the primary lymphoma site was defined as the cauda equina area. For further detailed pathological diagnosis, we performed surgical biopsy of the cauda equina. Morphological and immunohistochemical assessment made a diagnosis of diffuse large B-cell lymphoma of the cauda equina. The patient received radiotherapy to the lumbosacral area (50 Gy) and methotrexate (MTX) therapy after surgery. The patient was able to walk without help after the therapies. Follow-up MRI performed 1 year after biopsy showed remission of the lesion. MRI and spinal tap were effective tools for the early definitive diagnosis of cauda equina lymphoma. Combined treatment with radiotherapy and MTX should be performed as early as possible ²⁾.

Teo et al report a case, with literature review, discuss their clinical features, operative and histopathological findings. Although rare, with an increasing incidence of CNS lymphoma, they should be considered in the differential diagnosis of intradural lesions. Furthermore, with intraoperative smear to establish diagnosis, extensive surgery can be avoided. The controversial role of glucocorticoids in the management of these patients is also discussed ³⁾.