SOLITARY PLASMACYTOMA OF BONE AND EXTRAMEDULLARY PLASMACYTOMA - 2 DIFFERENT NOSOLOGICAL ENTITIES

Background: The relationship between solitary plasmacytoma and multipl e myeloma is still unclear, but they can be distinguished by their dif ferent clinical course. Indicators of disease activity and extension, and of a possible evolution to multiple myeloma, have not been identif ied as yet. Methods: Two cases of solitary plasmacytoma are described: one of the mandible and one extramedullary plasmacytoma (EMP) of the rhinopharynx. Pathologic data included immunohistochemical staining fo r heavy and light Ig chains, and for the proliferating cell nuclear an tigen (PCNA). Analysis of the peripheral immunological status and seru m parameters (beta 2 microglobulin, thymidine kinase, IL-2, IL-6 and s oluble IL-2 receptor) was performed and correlation was made with the clinical status. Flow cytometry analysis of nuclear DNA content and S- phase cell fraction were also studied in both neoplasms. Results: Soli tary plasmacytoma of bone (SPB) showed important basal immunologic alt erations and a marked increase in all serum parameters considered with respect to EMP. Ploidy analysis demonstrated an almost complete aneup loidy cell population for the SPB patient (80%), whereas in the EMP pa tient only 2% of the cells were aneuploid. The S-phase cells were 16% and 4%, respectively. PCNA index was 60% in SPB and 10% in EMP. Conclu sions: Solitary plasmacytoma of the bone appeared to be a more aggress ive form of plasmacellular neoplasia, distinct from EMP and similar to multiple myeloma. The study of serum parameters, together with analys is of PCNA, ploidy and S-phase fraction, can aid in better understandi ng disease activity, and in the choice of more adequate treatment. Mor eover, serial analysis of some serum factors might be useful markers f or monitoring the disease.