Plasma cell leukemia (PCL) is a very rare disease. We report two cases of PCL with complex chromosomal abnormalities: long arm trisomy and short arm partial monosomy of chromosome 1, a marker derived from chromosome 8, and monosomy 13 were found in both cases; other additional chromosome abnormalities were also present in each case. Bastard et al. reports two similar cases in this issue. Cytogenetic studies in PCL have seldom been reported in the literature: chromosomal abnormalities are most often complex: chromosomes 1, 8, 11, 13, and 14 are those most frequently involved. Such cytogenetic findings are observed in advanced multiple myeloma. Cytogenetic, clinical, and immunological findings observed in PCL and the advanced stage of multiple myeloma are arguments for the single origin of pathogenesis.