[Neurolymphomatosis of the sciatic nerve diagnosed by FDG-PET/CT].

Neurolymphomatosis is a rare manifestation of malignant lymphoma. The involvement of peripheral nerves has mostly been described as dissemination of a systemic lymphoma. In contrast, primary peripheral nerve lymphoma is extremely rare. A 68-year-old man presented in January 2014 with a sensory disturbance in the left lower extremity. There were no obvious findings on MRI or CT that could account for his symptoms. After 1 year of symptomatic treatment, the patient was managed conservatively for an additional year. However, his symptoms worsened. FDG-PET/CT showed high FDG uptake in the left sciatic nerve. Biopsy of the lesion revealed diffuse large B cell lymphoma.