[Peripheral neuropathies and monoclonal dysglobulinemias: contribution of morphological study].

The association between a peripheral neuropathy (PN) and a monoclonal dysglobulinemia has often been reported. A causative link is however not always easy to establish. Therefore, to demonstrate with certainty that the dysglobulinemia is actually responsible for the PN, various clinical, electrophysiological and immunological criteria are employed. As a result of our personal experience, we wish to emphasize the benefit of the histological and immunopathological findings revealed by the nerve biopsy of these patients. The nerve biopsy results have, in addition, been combined and compared with the results of an indirect immunofluorescence study of the sera of these patients on normal human nerve. The results of these studies have permitted us, in about 70% of cases, to ascertain the mechanisms in question: the role of an eventual chemotherapy, the dysimmune process, the presence of abnormal immunoglobulins in the nerve, amyloidosis deposits, infiltrations of nerve parenchyma by abnormal cells, a combination of one or several of these mechanisms, etc... We were able to divide our 70 patients into 4 groups: group 1: "direct link" (55-60% of the cases), group 2: "indirect link" (10-15%), group 3: "no link" (10%), and group 4: "undetermined link" (about 20%). Analysis of group 1 revealed a statistically significant association between PN and type IgM Kappa MGUS.