Solitary plasmacytoma of bone.

From 1978 to 1992, 19 patients were diagnosed with solitary plasmacytoma of bone (SPB) accounting for 5.5% of plasma cell neoplasms in Chang Gung Memorial Hospital. Fourteen were male and five were female, with ages ranging from 21 to 71 years (median, 53 years). M-protein was detected at diagnosis in five patients, and during follow-up in three. The most common sites of SPB were the vertebral bodies, with seven involving the thoracic, four involving the lumbar and two involving the cervical spine. The remaining sites included the skull in four, and femur and pelvis in one each. Fifteen of the patients received local radiotherapy, local control was achieved in all; nine patients were alive with no evidence of disease for seven to 77 months, two patients remained in apparent remission at 14 and 92 months, two patients progressed to multiple myeloma at 12 and 84 months, one patient developed extramedullary plasmacytoma at three months, and one patient died of intercurrent disease at four months. The four patients who were not treated with radiation therapy ultimately developed local recurrence or dissemination within four years. In our series, local recurrence or dissemination was always associated with the appearance of, or an increase in, the M-component; thus, measurement of M-protein is helpful in assessing tumor control or progression. Based on our experience and a review of the literature, it is recommended that irradiation of the primary sites is the treatment of choice. Chemotherapy is indicated in those patients with disease progression, recurrence, or dissemination.