Prognostic significance of morphological assessment of plasma cells in multiple myeloma

Multiple myeloma (MM) is a hematological malignancy caused by clonal proliferation of malignant plasma cells (PC). The aim of the work is to determine prognostic significance of morphological subtypes of PC in relation to overall treatment response, long-term survival and other conventional prognostic parameters. One hundred and thirty-nine newly diagnosed MM patients who underwent autologous transplantation in clinical trials conducted in one center were included. Percentual representation of subtypes of plasma cells in bone marrow was measured based on progressive analysis of nucleolus, nuclear chromatin and ratio of nuclei to the volume of cytoplasm (N/C ratio) creating 8 subtypes P000-P111 and four subclassifications of cells. Mature plasma cells (P000, P001) were found in 42.4% of patients; proplasmocytes I (P010, P011, P100) in 38.1% of patients, and proplasmocytes II (P101, P110) in 19.4% of patients. Patients who reached treatment response after autologous transplantation had statistically significant lower frequency of mature plasma cells than patients with no treatment response (median 24.0% vs. 36.0 %; p=0.032). Patients with mature plasma cells of subtype P000 an patients with value P000 ≥ 37% (median 46.8 months vs. 77.8 months; p = 0.020). Patients with proplasmocytes II subtype P110 rings valuable prognostic information and correlation with other prognostic factors as well as total treatment response and survival in MM patients who underwent autologous transplantation.