Spinal cord involvement in primary CNS lymphoma.

LETM is a common syndrome and the diagnosis of CNS lymphoma is not usually considered in the list of differentials. Primary CNS lymphoma can present as longitudinally extensive transverse myelopathy. Failure to suspect and evaluate leads to delay in diagnosis and treatment. PCNSL may be non contrast enhancing on gadolinium enhanced MRI. CSF analysis should be done preferably before starting corticosteroids as it is usual practice in treatment of transverse myelitis, as steroids may lead to transient improvement and mask the correct diagnosis. Repeated CSF examinations may be needed to clinch the diagnosis.