Monocytoid B cell lymphoma associated with antibodies to myelin-associated glycoprotein and sulphated glucuronyl paragloboside.

Monocytoid B cell lymphoma (MBCL) is an immunologically and morphologically well-defined low-grade lymphoma with a predilection for lymph nodes of the parotid region. We describe an association of MBCL with anti-myelin-associated glycoprotein (MAG) polyneuropathy in a 53-year-old male. The diagnosis of stage IV MBCL with nodular bone marrow infiltration, Sjögren's syndrome and sensorimotor polyneuropathy was made in October 1996. Serum immunoelectrophoresis demonstrated IgMkappa paraprotein. This was then cross-reacted with epitopes of MAG and sulphated glucuronyl paragloboside (SGPG) on myelin sheaths, and detected by thin layer chromatography and Western blot. Direct immunofluorescence of a sural nerve biopsy showed loss of myelin fibres, segmental demyelinization and IgM deposits on the myelin sheaths. The cerebrospinal fluid was normal. After six cycles of chemotherapy (ChlVPP protocol), all the patient's haematological parameters normalized accompanied by an improvement in neurological signs. The improvement of the polyneuropathy after chemotherapy indicates that the autoimmune anti-MAG and anti-SGPG antibodies resulted from the neoplastic lymphoid proliferation.