ABSTRACT
Plasma cell leukemia (PCL) may occur as an unusual manifestation of multiple myeloma (MM) and/or as a rare form of leukemia. Most authors have credited Foa (1904) with the first description,1 but this case report does not contain sufficient evidence for the diagnosis, and the first case may in fact be the patient reported by Gluzinski and Reichenstein in 1906.2
There are two forms of PCL: primary PCL (P-PCL), occurring de novo in patients without a pre-existing MM, first diagnosed in the leukemic phase (approximately 60% of the cases), and secondary PCL, arising as a late event in about 1% of patients previously diagnosed with MM and corresponding to a leukemic transformation.3,4
In historical series, the incidence of PCL has been estimated at 1-2% of patients with MM.3-5 In more recent series, the incidence of primary PCL has been estimated at between 2.6% and 4% of patients with MM,5-8 12% of patients with high tumor mass MM,8 and 0.9% (8/847) of patients with acute leukemia.6
