MORPHOLOGICAL FEATURES OF TUMORS SUBSTRATE IN MULTIPLE MYELOMA PATIENTS COMPLICATED WITH PLASMACYTOMA

Objective. To study the histological structure of bone marrow (BM) and plasmacytoma tumor substrate in patients with multiple myeloma (MM). Materials and methods. The study included 35 patients (19 men and 16 women) aged 23 to 73 years with newly diagnosed MM. At the first onset of the disease plasmacytoma was diagnosed in 21 patients: bone plasmacytoma, associated with skeletal bones – in 14 patients; extramedullary plasmacytoma, emerging in various organs not connected with bone tissue – in 7 patients. All patients underwent BM trephine biopsy and plasmacytoma biopsy with subsequent histological examination. BM and plasmacytoma histological specimens were studied using LEICA DM4000B microscope. Frequency domain analysis (cross tables, Fisher–Freeman test) was used for data statistical analysis.

Results. The analysis showed that the histological features of BM in MM patients with extramedullary plasmacytoma statistically significantly differed from that in MM patients with bone plasmacytoma and without plasmacytoma. As a result of the analysis, the relationship between BM morphological variant and tumor advancement became apparent. When comparing the morphological pattern of the bone and extramedullary plasmacytomas, no significant differences were found, however, the substrate of the extramedullary plasmacytoma was more often represented by tumor cells with immature morphology as compared to the substrate of the bone plasmacytoma.

Conclusion. The established differences in the histological structure of the BM in MM patients with extramedullary plasmacytoma suggest that this type of the disease stands apart and requires further detailed pathomorphological study.