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Primary plasma cell leukemia: consensus definition by the International Myeloma Working Group according to peripheral blood plasma cell percentage

Primary plasma cell leukemia (PCL) is a rare and aggressive form of blood cancer that is associated with a poor prognosis. ​ This document explores the diagnosis and prognosis of PCL in patients with multiple myeloma (MM). ​ It highlights the importance of accurately identifying circulating plasma cells in peripheral blood smears for the diagnosis of PCL. ​ The document proposes a new definition of primary PCL as the presence of 5% or more circulating plasma cells in patients with MM. ​ It suggests that these patients should be considered high-risk and should not be excluded from clinical trials. ​ The document also emphasizes the need for further research on the molecular characteristics of PCL and the development of effective treatment strategies. ​ It recommends the use of additional methods, such as slide-based immunofluorescence microscopy and flow cytometry, for the quantification of plasma cells in peripheral blood to detect early primary PCL. ​

List of important points:

  1. Primary plasma cell leukemia (PCL) is a rare and aggressive form of blood cancer with a poor prognosis. ​
  2. Accurate identification of circulating plasma cells in peripheral blood smears is crucial for the diagnosis of PCL. ​
  3. The proposed new definition of primary PCL is the presence of 5% or more circulating plasma cells in patients with multiple myeloma (MM). ​
  4. Patients with this new definition of primary PCL should be considered high-risk and should not be excluded from clinical trials. ​
  5. Further research is needed to understand the molecular characteristics of PCL and develop effective treatment strategies. ​
  6. Additional methods, such as slide-based immunofluorescence microscopy and flow cytometry, can be used to quantify plasma cells in peripheral blood and detect early primary PCL. ​
  7. Early detection and close monitoring of patients with a few circulating plasma cells is important, as they may rapidly progress to PCL. ​
  8. Aggressive treatment of patients with lower circulating plasma cells may lead to better outcomes, but this requires further investigation. ​
  9. The inclusion of patients with the new definition of primary PCL in clinical trials and reporting them as high-risk features is recommended. ​
  10. The standard treatment for multiple myeloma may not be sufficient to overcome the poor prognosis of patients with circulating plasma cells. ​
  11. Early enrollment into clinical trials using new agents is crucial to improve survival in patients with primary PCL. ​
  12. The document acknowledges the limitations of conventional cytology in establishing clonality of circulating plasma cells and suggests the use of flow cytometry immunotyping. ​
  13. The document highlights the urgent need for further studies on the genomic mechanisms of PCL. ​
  14. Addressing both ultra high-risk myeloma and PCL jointly can help overcome recruitment barriers for these patient populations.

Authors:

Carlos Fernández de Larrea, Robert Kyle, Laura Rosiñol, Bruno Paiva, Monika Engelhardt, Saad Usmani, Jo Caers, Wilson Gonsalves, Fredrik Schjesvold, Giampaolo Merlini, Suzanne Lentzch, Enrique Ocio, Laurent Garderet, Philippe Moreau, Pieter Sonneveld, Ashraf Badros, Gösta Gahrton, Hartmut Goldschmidt, Sascha Tuchman, Hermann Einsele, Brian Durie, Baldeep Wirk, Pellegrino Musto, Patrick Hayden, Martin Kaiser, Jesús San Miguel, Joan Bladé, S. Vincent Rajkumar & Maria Victoria Mateos 

Citation:

Blood Cancer J. 2021 Dec 2;11(12):192.
https://doi.org/10.1038/s41408-021-00587-0

 

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