Clinical course and survival in 16 patients with localized plasmacytoma.

The clinical course of 16 patients with localized plasmacytoma, 9 with solitary plasmacytoma of bone (SPB), and 7 with extramedullary plasmacytoma (EMP) are presented. Median follow up of SPB was 77 months and of EMP 74 months. The EMPs were localized in the upper respiratory tract (4 cases), the gastro-intestinal tract (2 cases) and the skin (1 case). The SPBs were localized in the ribs (3 cases), the spine (3 cases), the humoral bone (1 case), the skull (1 case) and the mandibular bone (1 case). In 3 patients with EMP and in 5 patients with SPB, the monoclonal protein could be determined at presentation. Local recurrences following surgical removal or irradiation occurred in 2 patients with EMP and in 1 patient with SPB after 12-60 months. Classical multiple myeloma developed in 3 patients with EMP and in 4 patients with SPB, 9-130 months after diagnosis. The monoclonal protein level proved to be a useful disease marker which (re)appeared at local recurrence or at dissemination. The median survival of the 16 patients with solitary plasmacytoma was 138 months, which is considerably longer than the median survival of 42 months in 14 stage-I patients with classical multiple myeloma who were observed during the same follow-up period.