An Approach to Identify a Biomarker for the Development of Secondary Plasma Cell Leukemia
Introduction/Background/Significance: Plasma cell leukemia (PCL) is defined as >2 × 109/liter plasma cells (PCs) in peripheral blood or by >20% in differential leukocyte count. Secondary PCL (sPCL) develops in 2% to 4% of multiple myeloma (MM) patients. No predictive biomarker for the development of sPCL is available.
Materials and Methods/Case Presentation/Objective: Among 160-180 new cases of plasma cell dyscrasia, we retrieved 17 PCL cases, pPCL (primary):sPCL ratio 9:8. The male to female ratio was 10:7. The age ranged from 39 to 71 years (mean, 55.2 years). Age was ≤50 years in 4 of 17 cases. The range for hemoglobin was 3.5 to 13.1 gm%, total leukocyte count was 2600 to 34,500/mm3, and platelet count was 15,000 to 23,000/mm3. PC in peripheral blood smear was 5% to 90% and in bone marrow aspirate (BMA) was 40% to 90%. B2 microglobulin (B2M) ranged from 1.1 to 12.6 mg/L. Statistical analysis was done to establish a correlation between pPCL and sPCL by using various clinical parameters including age, sex, hemoglobin, TLC, platelet count, plasma cell % in PS and BM, B2M, values of M-band, immunofixation, renal lesion, overall survival, kappa/lambda ratio, serum immunoglobins, and lactate dehydrogenase (LDH).
Results/Description/Main Outcome Measures: We could not find any significant correlation between pPCL and sPCL in the above-mentioned variables except LDH, which showed a differential trend between the two. LDH was higher in sPCL than in pPCL, the mean being 516 ± 290 and 213 ± 44.9, respectively, with p-value < 0.08.
Conclusions: In this pilot study, we can affirm that LDH may play a role in the prediction of sPCL in cases of MM, although the sample size was small. A high risk for PCL in MM is made up of cases with elevated blood LDH, B2M, and calcium with increased PC%, age, and low albumin.
