Teaching Case

A 31-year-old male presented with complaints of headache 1 month ago, facial pain, diplopia, left upper limb pain and lower limb numbness for 2 days.

Abnormal smooth thickening of bilateral oculomotor, trigeminal, and abducens nerves with subtle post-contrast enhancement (Figures 1a, 1b, 2, and 3). Diffuse smooth thickening of the cauda equine nerve fibres with complete effacement of the dural sac (Figure 4). Hypertrophy of the dorsal nerve root ganglion is seen at the C1–2 level on the left side (Figures 5a and 5b).

Background

Neurolymphomatosis (NL) is a process of direct infiltration of single or multiple peripheral nerve roots by malignant lymphoma cells, leading to a spectrum of neurological symptoms based on the affected nerves. The primary malignant cell type is predominantly diffuse large B-cell, with rare instances being secondary to peripheral T-cell lymphoma. Most commonly, it affects peripheral nerves, followed by spinal nerve roots, cranial nerves, and brachial and lumbar plexuses [1,2].

Clinical Perspective

The clinical presentation of NL typically includes progressive painful peripheral neuropathy or radiculopathy, cranial neuropathy with or without pain, painless polyneuropathy, and mononeuropathy multiplex [3]. Cranial neurolymphomatosis is present with single or multifocal neuropathy and cranial neuropathy dependent on the affected cranial nerve and the degree of infiltration with or without pain. The disease progression is often gradual, extending over months to years [4].

Imaging Perspective

MRI and FDG-PET CT are the commonly used modalities to evaluate neurolymphomatosis. It is essential to interpret imaging studies in conjunction with clinical manifestations and laboratory findings to reach an accurate diagnosis.

The MRI findings in neurolymphomatosis typically reveal diffuse fusiform thickening of nerves with or without nodularity and moderate to intense enhancement in post-contrast images. When observing STIR/T2-weighted images, the infiltrated nerves exhibit increased signal intensity with peritumoral oedema [1,3,5].

In patients with relevant clinical history and corresponding abnormal MRI results, the presence of elevated FDG activity along a nerve root or peripheral nerve on FDG-PET indicates a likelihood of neurolymphomatosis [1].

CT imaging often falls short in revealing abnormalities of nerve roots or peripheral nerves in individuals with neurolymphomatosis.

While nerve biopsy is regarded as the gold standard for diagnosis, it is an invasive procedure that poses a risk of causing permanent nerve damage. In our patient, stellate ganglion biopsy revealed infiltration by lymphomatous cells.

Outcome

The best treatment for neurolymphomatosis is still uncertain. However, chemotherapy (both systemic and intrathecal) along with radiotherapy are commonly employed and effective in current practice. In recent years, there has been an increased utilisation of high-dose MTX for treating neurolymphomatosis due to its capability to penetrate the blood-brain or blood-nerve barrier and its effectiveness in primary CNS lymphoma [4,6].

Take Home Message

Neurolymphomatosis is a very rare condition involving one or multiple peripheral nerve roots. Nerve root thickening and enhancement along with clinical and laboratory findings are mandatory to reach a final diagnosis.

All patient data have been completely anonymised throughout the entire manuscript and related files.