Extramedullary Relapse of Multiple Myeloma - Plasma Cells Characteristics.
|Fakulta / Pracoviště MU|
|Popis||Multiple myeloma (MM) is the second most common hematological malignancy in the world. The introduction of new drugs (thalidomide, bortezomib, revlimid) has dramatically improved survival of MM patients, but MM still remains an incurable disease. Unfortunately, an increase in the incidence of extramedullary relapse of MM (EM), an aggressive mostly resistant entity with abysmal prognosis for patients has been reported. EM can affect any area of tissue - soft tissue involvement can be with or without relationship to bone. A recent study of 936 MM patients by Usmani et al (2012) reported presence of EM in the skin and soft tissues at the time of diagnosis while liver involvement was common at relapse or progression. Aims: The objective of this study was to evaluate cytogenetic and flowcytometric data of available set of EM patients, and also to compare characteristics of plasma cells isolated from bone marrow and the extramedullary tumor. Conclusion: Chromosomal abnormalities connected to worse prognosis are more common in EM patients. PC phenotype seems to be different in cells obtained from BM and EM tumor. PC from EM tumor had significantly lower expression of CD27 and CD19. CD27 is a tumor necrosis factor receptor and plays a key role in regulating B-cell activation and immunoglobulin synthesis. Its low expression could be one of the main reasons for resistance in MM while loss of CD19 can create a proliferative advantage for the malignant plasma cell clone. Other interesting markers are CD54 and CD56 which were non-significantly decreased. CD54 also known as ICAM-1 plays a key role in stabilizing cell-cell interactions and migration, and CD56 (NCAM) is important for adhesion of PC to the bone marrow microenvironment. CD54 and CD56 lower expression may be the reason for EM development in MM but their role needs to be further elucidated.|