Diffuse large B-cell lymphoma of the cauda equina.

Primary central nervous system (CNS) lymphoma is a rare form of non-Hodgkin's lymphoma. The clinical presentation is variable, depending on its localisation within the nervous system. Only 1% of primary CNS lymphoma emerges in the spinal cord, and the prevalence of primary lymphoma of the cauda equina is unknown, but probably even rarer. Diagnosing primary lymphoma of the cauda equina is difficult, since it can mimic other more common disorders such as a herniated disc, especially in its early stages. Here we present two cases of primary cauda equina lymphoma in which diagnostic work up took a long time, as the final diagnosis was only reached after a nerve root biopsy. 2014 BMJ Publishing Group Ltd.