Magnetic Resonance Imaging Spectrum of Cauda Equina and Conus Lymphoma: Keys to Unravel the Differential Diagnosis with a Review of the Literature

Abstract Deb K. Boruah Central nervous system lymphoma is not an uncommon condition, but spinal lymphoma with isolated involvement of the conus medullaris and cauda equina is a rare entity. Our study aims to evaluate the various magnetic resonance imaging (MRI) features of cauda equina and conus lymphoma. This retrospective study was carried out on nine patients with histopathologically proven cauda equina and conus lymphoma, who were presented at a tertiary care hospital between January 2018 and June 2020. All patients underwent lumbar spine MRI scans using a 1.5 Tesla MR scanner. The clinical data and different MRI findings were analyzed with an independent sample t -test and paired-samples t -test. Among the nine patients with cauda equina and conus lymphoma, three had primary lymphoma and six had secondary lymphoma. Six patients (66.7%) showed a diffuse pattern of involvement of cauda equina and conus medullaris, while three patients (33.3%) showed a focal pattern. T2-weighted imaging (T2WI) hypo to isointense signal intensity lesions were observed in six patients (66.7%) and T2WI iso to slight hyperintensities in three patients (33.3%). Diffuse sheet-like thickening and postcontrast enhancement of the thickened cauda equina nerve roots were observed in two patients of primary and one patient with secondary lymphoma. The diagnosis of cauda equina and conus lymphoma especially primary lymphoma is challenging and requires a high index of clinical suspicion as distinguishing this entity from similar conditions is difficult solely on MRI. Early diagnosis of this entity is important for early institution of treatment for increasing the chances of survival and improvement of symptoms.