Prognostic impact of circulating plasma cells in patients with multiple myeloma: implications for plasma cell leukemia definition.

The presence of circulating plasma cells in patients with multiple myeloma is considered a marker for highly proliferative disease. In the study herein, the impact of circulating plasma cells assessed by cytology on survival of patients with multiple myeloma was analyzed. Wright-Giemsa stained peripheral blood smears of 482 patients with newly diagnosed myeloma or plasma cell leukemia were reviewed and patients were classified into 4 categories according to the percentage of circulating plasma cells: 0%, 1-4%, 5-20%, and plasma cell leukemia with the following frequencies: 382 (79.2%), 83 (17.2%), 12 (2.5%) and 5 (1.0%), respectively. Median overall survival according to the circulating plasma cells group was 47, 50, 6 and 14 months, respectively. At multivariate analysis, the presence of 5 to 20% circulating plasma cells was associated with a worse overall survival (relative risk 4.9, 95% CI 2.6-9.3) independently of age, creatinine, the Durie-Salmon system stage and the International Staging System (ISS) stage. Patients with ≥5% circulating plasma cells had lower platelet counts (median 86×109/L vs 214×109/L, P<0.0001) and higher bone marrow plasma cells (median 53% vs 36%, P=0.004). The presence of ≥5% circulating plasma cells in patients with multiple myeloma has a similar adverse prognostic impact as plasma cell leukemia.

Evaluation of low platelet counts by optical, impedance, and CD61-immunoplatelet methods: estimation of possible inappropriate platelet transfusion.

BACKGROUND: The Cell-Dyn Sapphire (Abbott Diagnostics) detects platelets (PLTs) with a CD61 monoclonal antibody directed against glycoprotein IIIa as well as impedance (IMP) and optical (OPT) technology. We decided to evaluate low PLT counts produced by IMP and OPT methods and to compare them with the CD61 method. We also examined the possibility of inappropriate PLT transfusion resulting from an inaccurate PLT count. STUDY DESIGN AND METHODS: We analyzed consecutive blood samples with OPT PLT counts of less than 50 x 10(9)/L. We performed the PLT count with the OPT, IMP, and CD61 methods and we compared the number of prophylactic PLT transfusion indications according to the PLT counts determined by the OPT and IMP methods with the number of prophylactic PLT transfusion indications according to our reference CD61 method. RESULTS: We collected 135 samples. In the bias analysis, the OPT method and the IMP method showed higher PLT counts when compared with the CD61 method (mean of difference 1.69 x 10(9) and 19.1 x 10(9)/L, respectively). We saw overtransfusion in 1.5% of cases and undertransfusion in 15.2% of cases (p = 0.01; McNemar's test) when we selected a threshold of 10 x 10(9)/L with the OPT method. We saw undertransfusion in 22.2% of cases (p = 0.03; McNemar's test) when we selected a threshold of 5 x 10(9)/L with the OPT method. CONCLUSIONS: Low PLT counts determined by the OPT and IMP methods showed some disagreement when compared with the CD61 method. This disagreement caused both PLT undertransfusion and overtransfusion.