A Review of Three Cases of Primary Plasma Cell Leukemia: Incidental Finding Discovered by Blood Smear Revision

Abstract

Introduction: Plasma cell leukemia (PCL) is the most aggressive variant of the monoclonal gammopathies (MG). Its diagnosis is based on standard morphological examination of peripheral blood, by finding plasma cells with an atypical morphology. The International myeloma working group (IMWG) has updated the diagnostic criteria for PCL considering that patients with newly diagnosed MG with 5% or greater plasma cells in peripheral blood should be considered as PCL. Case report: We present three cases of primary PCL that were admitted to the hospital due to the study of an anaemia and whose diagnosis was an incidental finding. All the patients had >5% of circulating plasma cells, whose clonality and aberrant phenotype was determined by peripheral and blood marrow flow cytometry immunophenotype and all of them had high-risk cytogenetics related with a poor and adverse outcomes of the disease. Discussion: This cases highlight the importance of peripheral blood smear revision, because the identification of aberrant plasma cells leaded the diagnosis of the MG and the patients were able to start treatment as soon as possible. Carefully examination and interpretation of peripheral blood smear should be always performed, with special attention in patients with a suspicion of MG, because with the new IMWG definition, it is possible that this entity is underdiagnosed.