Sciatic nerve neurolymphomatosis as the initial presentation of primary diffuse large B-cell lymphoma: a rare cause of leg weakness

Abstract

Neurolymphomatosis (NL) is defined as the involvement of the peripheral nervous system in lymphocytic invasion. It is a very rare form of lymphoma that may occur as an initial presentation or recurrence. It affects various peripheral nervous structures and can therefore mimic disc-related nerve root pathology or compressive mononeuropathy. NL often occurs in malignant B-cell non-Hodgkin lymphomas. Notwithstanding its aggressiveness or intractability, NL should be discriminated from other neurologic complications of lymphoma. Herein, we present a case of primary NL as the initial presentation of diffuse large B-cell lymphoma (DLBCL) of the sciatic nerve. The patient presented with weakness and pain in his left leg but had no obvious lesion explaining the neurologic deficit on initial lumbosacral and knee magnetic resonance imaging (MRI). NL of the left sciatic nerve at the greater sciatic foramen was diagnosed based on subsequent hip MRI, electrodiagnostic test, positron emission tomography/computed tomography, and nerve biopsy findings. Leg weakness slightly improved after chemotherapy and radiotherapy. We report a case wherein NL, a rare cause of leg weakness, manifested as the initial presentation of primary DLBCL involving the sciatic nerve at the greater sciatic foramen.

Keywords: Diffuse large B-cell lymphoma; Neurolymphomatosis; Neuropathy; Sciatic nerve.

Fig. 1.

Magnetic resonance images of the lower extremity (A) before and (B) after treatment. (A) An enlarged fusiform mass of approximately 6.3×2.9×2.8 cm (arrows) is seen at the left greater sciatic foramen from the L5 and S1 nerve roots to the sciatic nerve with abnormal progressive gadolinium enhancement and a non-enhancing central portion on axial and coronal T1-weighted images. (B) Markedly decreased size of the enhancing mass (arrow) at the left greater sciatic foramen with mild thickening and residual enhancement of the sciatic nerve after the fourth session of chemotherapy. Left gluteal muscle atrophy (arrowhead) is seen.

Fig. 2.

Histopathologic findings of the needle biopsied soft tissue adjacent to the left sciatic nerve. (A) Large, irregularly-shaped lymphoid cell proliferation with a diffuse pattern. These atypical lymphoid cells have a large nucleus with clear perinuclear space due to shrunken cytoplasm (hematoxylin and eosin stain, ×400). (B) Immunohistochemical stain shows large lymphoid cells that are positive for CD20 (immunohistochemical stain, x400).

Fig. 3.

Axial and coronal fluorodeoxyglucose positron emission tomography/computed tomography images of the lower extremity (A) before and (B) after treatment. (A) Diffuse increased uptake in the left sciatic nerve and a few hypermetabolic foci (arrows) at the left presacral area and pelvic cavity. (B) Complete metabolic resolution of the left sacral foramen mass and partial metabolic resolution of the hypermetabolic foci at the left presacral area and pelvic cavity after the third session of chemotherapy.