Extramedullary plasmacytoma: clinical and histopathologic study

To review the histories of extramedullary plasmacytoma patients diagnosed in Slovenia between 1969 and 1999, to determine the relationship between radiotherapy (XRT) dose and local tumor control, and to clarify the role of elective nodal XRT and the prognostic value of Bartl's histologic grading criteria (originally devised for multiple myeloma [MM]).

The database of the Cancer Registry of Slovenia was used for the identification of patients. The inclusion criteria were as follows: bone marrow biopsy showing less than 10% plasma cells, normal skeletal survey, and immunohistochemically determined tumor monoclonality. Simulation/portal films were reviewed to assess the extent of elective nodal XRT.

Twenty-six patients with 31 tumors fulfilled the inclusion criteria. In 4 patients, nine metachronously appearing solitary tumors were diagnosed. The head-and-neck region and other body sites were the sites of origin of primary tumors in 84% and 16% of patients, respectively, whereas in the two regions, regional disease was seen in 15% and 60% of patients, respectively. Therapy was as follows: XRT, 12 patients; surgery and postoperative XRT, 15 patients; and surgery, 4 patients. Ultimate local and regional control rates were 90% and 97%, respectively, and MM developed in 2 (8%) patients. The 10-year disease-specific and overall survival rates were 87% and 61%, respectively. The analysis of the dose-effect relationship showed that more conservative treatment is justified: for macroscopic disease, 40-50 Gy (2 Gy/day), adjusted to the bulk of disease; for microscopic disease, 36-40 Gy; after R0 surgery, no XRT is required, but close observation is needed. No attempts should be made to treat uninvolved nodal regions. Using Bartl's histologic grading criteria, trends were detected in patients with higher tumor grades: regional lymph node involvement (p = 0.04) and shorter disease-specific survival (p = 0.08).

Extramedullary plasmacytoma is a highly curable disease when XRT is used with or without previous surgery. The rate of conversion to MM is low. Moderate-dose XRT using limited fields is recommended. The prognostic value of Bartl's grading system needs further evaluation.