The Diagnostic Dilemma of Neurolymphomatosis

Abstract

Neurolymphomatosis (NL) defined as infiltration of the central nervous system or the peripheral nervous system (PNS) by malignant lymphoma cells is a rare clinical entity. However, the increasing use of fluorodeoxyglucose positron-emission tomography (FDG-PET) and magnetic resonance imaging in evaluating PNS disorders is resulting in; this condition being recognized more frequently. Here; we report five NL patients and review the current literature. We report five patients with non-Hodgkin's lymphoma (NHL) and NL, all of whom were men aged 47-69 years. The clinical presentation varied from symmetrical peripheral neuropathy to mononeuropathy. Peripheral neuropathy was the presenting manifestation of a systemic lymphoma in two patients (40%). Neuroimaging as well as whole-body FDG-PET helped in determining the correct diagnosis in all of the patients. NL is an unusual presentation of NHL resulting from infiltration of the PNS by malignant lymphomatous cells. While evaluating peripheral neuropathy, a high degree of suspicion of NL is required since the presenting symptoms vary, conventional radiology has only modest sensitivity, and a pathological diagnosis is often difficult. FDG-PET helps in the early diagnosis and treatment of this condition.

Keywords: diffuse large-B-cell lymphoma; fluorodeoxyglucose positron-emission tomography; mononeuropathy; neurolymphomatosis.

Fig. 1. Nerve bundle infiltration (patient 1), FDG-PET and MRI of right sciatic nerve (patient 2). A: A nerve bundle with infiltration by lymphoma cells (patient 1). B: CD 20 stain highlights diffuse infiltration by diffuse large B cells (patient 1). C: PET CT showing intense FDG uptake in right sciatic nerve (yellow arrow) (patient 2). D: intense enhancement of right sciatic nerve (arrow) on T1 weighted contrast MRI (patient 2).

Fig. 2. FDG-PET images (patient 4) and MRI Brain images (patient 5). A: FDG-PET showing intense uptake (white arrow) in the left testis (patient 4). B and C: Thickened and enhancing trigeminal nerves (yellow arrows) on fluid-attenuated inversion recovery and T1-weighted MRI, respectively (patient 5). FDG-PET: fluorodeoxyglucose positron tomography, MRI: magnetic resonance imaging.

Fig. 3. Nerve Biopsy staining (patient 4). A: Hematoxylin and eosin-stained nerve biopsy sample that appears relatively normal at low magnification. B: High-power view of the same sample showing a few large atypical lymphoid cells (yellow arrows) amidst Schwann cells. C: CD20 immunostaining highlights these lymphoma cells (red arrows). D: The same cells were negative for CD3 immunostain (black arrows) (patient 4).

Fig. 4. FDG-PET images (patient 5). A: Intense diffuse FDG uptake (white arrows) in the periphery of both cerebellar hemispheres and the cervical cord. B and C: Intense diffuse FDG uptake (white arrows) in the thickened spinal cord in axial and saggittal sections, respectively (maximum standard uptake value of 25.9) (patient 5). FDG-PET: fluorodeoxyglucose positron tomography.