plasma cell dyscrasia; called primary PCL when it is diagnosed inthe leukemic phase, and secondary PCL when there is leukemic transformationof a previously recognized multiple myeloma

proliferation involving plasma cell expressingcytoplasmic immunoglobulin, CD38, plasma cell antigene 1; a minority ofcells express CD10, HLA-DR, and CD20; the nature of the clonogenic cell inmultiple myeloma is unknown; the presence of multiple hematopoietic surfaceantigenes on malignant plasma cells suggests its origin from a pluripotentstem cell

rare disorder; approximately 60% of patients have the primary form; affects patients of more than 40 years of age; patients with primary PCL are younger than patients with the secondary PCL; slightly more frequent in men than in women.

patients with primary PCL have a greater incidence ofhepatosplenomegaly and lymphadenopathy, and fewer lytic bone lesions; blooddata: these data are similar to those of multiple myeloma, except thatthere are circulating plasma cells: patients with PCL have more than 20%plasma cells in their peripheral blood and an absolute plasma cell countequal or above 2000/mm³; additionnally, patients with primary PCL have higher plateletscounts and smaller M components compared to patients with secondary PCL

evolution: this disease is usually progressive; secondary PCL rarely responds to chemotherapy because patients already received alkylating agents and became resistant to them; in the primary form, responses have been observed with melphalan and prednisone; the response rate seems to be higher with combination therapy than with single alkylating agents; prognosis: the overall survival is short (few months).

Cytogenetic aberrations are detected more frequently in PCL than in multiple myeloma; the percentage of abnormal cases varies in different series but seems to be more than 50%; the overall pattern of cytogenetic changes is very similar to the pattern observed in multiple myeloma; numerical changes and/or structural aberrations have been described; in large series, hyperdiploidy is observed in 61 to 68% of cases, whereas pseudodiploidy and hypodiploidy occur in 9 to 20 and 10 to 30% of patients, respectively; monosomy 13 and trisomy 9 are the most frequent numerical abnormalities; hypodiploidy is more common in PCL than in myeloma. Apart from chromosome 9, gains also involve chromosomes 3, 5, 7, 11, 15, and 19, whereas losses also involve chromosome X and Y; structural aberrations mainly involve chromosome 14, with 14q+ resulting from translocation t(11;14)(q13;q32) or other changes (e.g. Burkitts translocations); chromosomes 16 (p or q), 1 (p or q), 19 (p or q), 6q, 17q, 2p and 7q might also be involved.

Chromosomal changes are detectable by conventional cytogenetic techniques or by FISH; in addition, comparative genomic hybridization showed to be a useful tool in PCL, allowing assessment of regions showing copy number changes.