[Extramedullary plasmacytoma forming a mass in the epidural space of the spinal cord: report of a case].

Plasmacytoma often forms an intramedullary mass in the vertebrae with absorption of trabecula and cortex of the bone. However, occasionally, it forms a mass in the extramedullary space of the vertebrae. The authors report such a rare case with plasmacytoma which formed a mass in the thoracic epidural space without evidence of involvement of the adjacent vertebra. On May 22, 1985, a 80-year-old man was admitted to our clinic with chief complaints of gait disturbance and hypesthesia below the umbilical level. Difficulty of walking developed approximately four months prior to admission with gradual aggravation and hypesthesia added thereafter. Neurological examinations at admission showed paraparesis with positive Babinski's and Chaddock's reflexes, hypesthesia and disturbances of vibration and position senses below the 9th thoracic nerve level. Myelography and CT scan using metrizamide indicated a presence of epidural mass at the 8th to 9th thoracic vertebrae. There was no abnormal bony change in the spine on plain X-ray and CT scan. On May 30, 1985, total removal of epidural tumor was performed by removing the laminae from the 7th to 10th vertebrae. Histological examinations including immunological stainings showed a plasmacytoma which produced monoclonal immunoglobulin of IgG-lambda type. Radiation therapy was not carried out. The serum protein fraction, immunoglobulin, immunoelectrophoresis, Bence-Jones protein and CSF immunoglobulin examined after operation, supported a histological diagnosis of plasmacytoma. Also, slight proliferation of plasma cells was noted in the bone marrow and peripheral blood.(ABSTRACT TRUNCATED AT 250 WORDS)