Plasma cell neoplasia with peripheral polyneuropathy. A study of five cases and a review of the literature.

Peripheral polyneuropathy (PPN) is a rare complication of plasma cell neoplasia (PCN), occurring in less than one percent of the patients. Fifty-four such patients (including our 5) were reviewed. There were 42 men (78%) and 12 women (22%) aged 28 to 72 years. Forty-nine percent of patients were younger than 51 years at the time of diagnosis. The initial complaints were different from those observed in multiple myeloma in general, and were related to polyneuropathy in 80% of the patients. PPN was usually of a mixed sensory-motor type and most often involved all four extremities. Skeletal pain was less common than in myeloma in general, occurring initially in 15% and at diagnosis in 45% of the patients. In 21 patients, reversibility of neuropathy was observed. These patients were compared to those with irreversible neuropathy and found to be relatively younger and more aggressively treated with irradiation and modern chemotherapy. Elevated sedimentation rate was uncommon. Less than half of the patients had anemia, and six patients, all with osteosclerotic lesions, had polycythemia. Azotemia was detected in 44% of the cases. No hypercalcemia was observed in 21 examined patients. M components were usually of IgG class, and when the light chains of M components were examined they were invariably of lambda type. Often the level of M component was below 2.0 g/dl. In all patients the bone marrow was infiltrated with immature, abnormal-looking plasma cells, but the infiltrate was often limited to one or a few foci. Solitary plasmacytoma was observed in 14 patients. No anemia, hypercalcemia or azotemia was recorded in this group. Eight patients had serum M components. Bone marrow aspirate was usually normal. In seven patients definite reversibility of PPN was observed after irradiation of plasmacytoma. Twelve patients presented with osteosclerotic lesions (22%), 18 with both osteosclerotic and osteolytic lesions (33%) and 13 with osteolytic lesions. Forty-two percent of the patients had less than three visible lesions in the skeleton. Eleven patients had either osteoporosis or radiologically normal skeleton. The mean survival from the first symptom was about 28 months and from the diagnosis 20 months. The five-year survival was 21% and 20%, respectively. These observations highlight the differences between PCN with PPN and multiple myeloma without PPN.