Abstract
BackgroundTo study the histological structure and immunohistochemical (IHC) parameters of the plasmacytoma tumour substrate in patients with multiple myeloma (MM).MethodsThe study included 21 patients (10 men/11 women) aged 23 to 73 years old with newly diagnosed MM complicated by plasmacytoma. Bone plasmacytoma was diagnosed in 14 patients, and extramedullary plasmacytoma was diagnosed in 7 patients. Plasmacytoma tissue specimens were examined using a LEICA DM4000B microscope. Anti-CD56, anti-CD166, anti-CXCR4, anti-Ki-67, and anti-c-MYC antibodies were used for IHC study of plasmacytoma biopsies.ResultsWhen comparing the morphology of bone and extramedullary plasmacytoma, no significant differences were revealed; however, the substrate of extramedullary plasmacytoma was more often represented by tumour cells with an immature morphology than was the bone plasmacytoma substrate (57.1% vs. 28.6%, respectively). We revealed a significant difference in the expression of CD166 between bone and extramedullary plasmacytoma. The mean values of CD166 expression in bone plasmacytoma cells were significantly higher (36.29 ± 7.61% versus 9.57 ± 8.46%, respectively; p = 0.033) than those in extramedullary plasmacytoma cells. We noticed that in extramedullary plasmacytoma cells, there were higher values for the Ki-67 index than in bone plasmacytoma cells, and this result was independent of cell morphology.ConclusionThe mechanisms involved in the dissemination of tumour plasma cells are currently unexplored. Even in such a small sample, some differences in expression could be identified, which may indicate that different mechanisms lead to the formation of bone and extramedullary plasmacytomas. Specifically, the expression of CD166 in extramedullary plasmacytoma cells was almost 4 times lower than that in bone plasmacytoma cells, which may indicate the involvement of CD166 in the mechanisms of bone destruction. The proliferative activity of extramedullary plasmacytoma cells was shown to be higher than that of bone plasmacytoma cells.
Highlights
The introduction of highly sensitive imaging methods into clinical practice has facilitated the more frequent detection of bone and extramedullary plasmacytoma in patients with multiple myeloma (MM)
When comparing the morphological patterns of bone and extramedullary plasmacytoma, no significant differences were revealed; the substrate of extramedullary plasmacytoma was more often represented by tumour cells with an immature morphology than was that of bone plasmacytoma (57.1% vs. 28.6%, respectively)
It was demonstrated that the mean Ki-67 values in extramedullary plasmacytoma cells were significantly higher (p = 0.004) than those in Histological examination of plasmacytoma in MM patients Depending on the cell composition, 2 morphological variants were distinguished in the plasmacytoma biopsy specimens: Variant I: massive infiltration by mature plasma cells; and
Summary
The introduction of highly sensitive imaging methods into clinical practice has facilitated the more frequent detection of bone and extramedullary plasmacytoma in patients with multiple myeloma (MM). According to the results of clinical studies, it has been revealed that in patients with newly diagnosed MM, the occurrence of plasmacytoma varies from 3.5 to 18%, and in patients with relapse of the disease, it varies from 6 to 30% [1, 3,4,5,6,7,8]. The variability in these values is due to the lack of clear terminologydefining criteria. To study the histological structure and immunohistochemical (IHC) parameters of the plasmacytoma tumour substrate in patients with multiple myeloma (MM)
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