Increasing importance of 18F-FDG PET in the diagnosis of neurolymphomatosis.

Neurolymphomatosis (NL) is a rare clinical entity that is defined as infiltration of the nervous system by a known or unknown haematological malignancy and is difficult to diagnose. Fluorine-18 fluorodeoxyglucose (18F-FDG) PET imaging is increasingly being used in haematological malignancies. This article focus on the role of 18F-FDG PET in the diagnosis and management of NL by presenting a review of cases described in the literature. Reports on NL that used PET with or without computed tomography (CT) as a diagnostic modality were extracted from Medline and evaluated. A total of 58 patients described in 49 case reports on NL were found. In 36 distinctive patients 18F-FDG PET with or without CT was used as a diagnostic modality. In 91% of patients PET showed uptake in various structures in the central or peripheral nervous system, suggesting involvement of lymphoma. Predilection localizations were the brachial and lumbar plexuses, along the course of peripheral nerves of the extremities, and the trigeminal nerve root. MRI, cerebrospinal fluid or bone marrow analysis were frequently negative. In the cases described in the literature 18F-FDG PET assisted in diagnosing NL by providing a whole-body evaluation, showing frequent uptake in affected nervous structures and supported disease management by defining a target for biopsy, monitoring progression and evaluating response to treatment. As other diagnostic methods may be negative, the importance of PET-CT is increasing in the diagnosis and management of this rare clinical entity.