[Plasma cell leukemia: a highly aggressive monoclonal gammopathy with a very poor prognosis].

Plasma cell leukemia (PCL) is an aggressive variant of multiple myeloma and is characterized by the presence of greater then 20% absolute number of plasma cells circulating in the peripheral blood. PCL represents approximately 2-4% of all MM diagnosis and exists in two forms: primary PCL (PPCL, 60% of cases) presents de novo; whereas secondary PCL (SPCL, accounts for the remaining 40%) consists of a leukemic transformation in patients with a previously diagnosed MM. Because the mechanisms contributing to the pathogenesis of PCL are not fully understood, immunophenotyping, genetic evaluation (conventional karyotype, FISH, GEP and array-CGH), and immunohistochemistry are very important tools to investigate why plasma cells escape from bone marrow and become highly aggressive. Since treatment with standard agents and steroids is poorly effective, a combination of new drugs as part of the induction regimens and haematopoietic stem cell transplantation (autologous and allogeneic approaches) may overcome the poor prognosis exhibited by PCL patients.