[Neurolymphomatosis].

Neurolymphomatoses (NL) are defined as the direct infiltration of the peripheral nervous system (PNS) by lymphomatous or leukaemic cells. The diagnosis of this rare disease is complex, typically relying on peripheral nerve histology, an invasive examination with a risk of sequelae. This diagnostic entity should be considered in the presence of a painful neuropathy, sometimes severe, whether or not associated with immunohaematological abnormalities, and in cases of resistance to first-line immunomodulatory treatments. NLs are classified into primary, which are limited to or originate from the peripheral nerve, and secondary NLs resulting from systemic involvement. The epineurium, the perineurium and the endoneurium might be affected. Diffuse large B-cell lymphomas are the most frequent histological entity, followed by marginal zone and lymphoplasmacytic lymphomas. The genesis of these infiltrations and their links with primary central nervous system lymphomas are not clearly established. In the future, the contribution of multimodal imaging techniques (whole-body PET, plexus MRI, nerve ultrasound) and sensitive technologies for detecting lymphoid clones (molecular biology, immunophenotyping) as well as therapeutic sequences will need to be clarified by dedicated multicentre studies.