Neurolymphomatosis: MRI and (18) FDG-PET features

Neurolymphomatosis (NL) is a rare presentation of lymphoma or leukemic infiltration of cranial or peripheral nerves. It is distinct from subarachnoid seeding of lymphoma as well as perineural tumour seen in epidural lymphoma. This rare condition has been reported mainly in oncology literature. Imaging features of solitary nerve involvement mimics, among others, peripheral nerve sheath tumours. We present the MRI and (18) fluorodeoxyglucose positron emission tomography ((18) FDG-PET) features of three cases of NL. MRI demonstrated variable appearances: infiltrative mass displacing neural fascicles, diffuse thickening and enhancement, and thickening of individual neural fascicles. (18) FDG-PET demonstrated avid uptake in all cases, two of which revealed skip lesions of the same nerve. The diagnosis of NL was confirmed by uncomplicated CT-guided biopsy of the affected sciatic nerve in one patient.