[Polyneuropathy and solitary bone plasmacytoma. A new case].

The authors report a case of acute polyneuropathy revealing a solitary osseous plasmacytoma with osteo-dense and osteolytic bone lesions. Initially, the rapid progression of the sensory and motor loss led to treatment by plasma exchanges and irradiation of the plasmacytoma. Four months later, despite a significant improvement of the neurological condition, serum protein electrophoresis continued to show a peak of monoclonal immunoglobulin. Chemotherapy with cyclophosphamide and prednisone was administered for one year whilst the neuropathy continued to regress. This case, which presents many classical features of plasma cell dyscrasia (polyneuropathy with albumino-cytological dissociation, radiological osseous condensation, low concentrations of lambda light chain protein), illustrates some unusual features of solitary plasmacytomas associated with peripheral neuropathy: the young age of our patient, an acute progression of the neuropathy in the early stages, tumoral localisation in the diaphysis of a long bone.