# Cranial Neurolymphomatosis Presenting With Trigeminal Neuralgia and Facial and Vagus Nerve Palsies Visualized on Fluorodeoxyglucose Positron-Emission Tomography (FDG PET)

## TL;DR

A rare case of cranial neurolymphomatosis in a lymphoma patient was detected using FDG PET imaging, showing neurological symptoms like trigeminal neuralgia and nerve palsies.

## Contribution

This case highlights FDG PET's utility in diagnosing cranial neurolymphomatosis and emphasizes the need for clinical vigilance in relapsed lymphoma patients.

## Key findings

- FDG PET revealed hypermetabolism in the left trigeminal nerve, pons, and jugular foramen.
- Vagus nerve involvement was visualized as vocal cord palsy on FDG PET.
- Neurological manifestations were linked to neurolymphomatosis in a DLBCL relapse.

## Abstract

Neurolymphomatosis (NL) is a rare and severe complication of lymphoma, characterized by lymphoma disease involvement in the central or peripheral nervous system. It is often associated with non-Hodgkin lymphoma, particularly diffuse large B-cell lymphoma (DLBCL), and is more frequently encountered in the setting of relapse. We report a case of a 68-year-old woman with stage IV DLBCL who relapsed after first-line treatment. She developed neurological manifestations, including trigeminal neuralgia, facial and vagus nerve palsies on relapse. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed. Florid FDG hypermetabolism was seen at branches of the left trigeminal nerve, left-sided pons, and left jugular foramen. Associated vocal cord palsy resultant from vagus nerve involvement was also visualized on FDG PET. Our case demonstrates the characteristic FDG PET imaging findings of cranial nerve NL, as well as highlights the importance of maintaining high clinical vigilance for NL and the usefulness of FDG PET imaging in the evaluation of NL.