Low versus high cell turnover in diffusely growing non-Hodgkin's lymphomas

Area of Science:

• Hematopathology
• Oncology
• Cell Biology

Background:

• Quantitative cellular kinetic analyses of neoplastic disorders often overlook cell loss, a critical factor in population dynamics.
• Non-Hodgkin's lymphomas (NHLs) exhibit complex cellular kinetics that require refined analytical parameters for accurate subtyping and prognosis.

Purpose of the Study:

• To evaluate the utility of a novel 'turnover index' (TI) as a parameter in quantitative cellular kinetic analyses of non-Hodgkin's lymphomas (NHLs).
• To assess the correlation between TI, lymphoma subtypes, Ki-67 expression, and overall patient survival.

Main Methods:

• Retrospective analysis of 170 cases of various types and subtypes of non-Hodgkin's lymphomas (NHLs).
• Calculation of the 'turnover index' (TI) by summing the mitotic index and the apoptotic index for each case.
• Cluster analysis of TI plotted against the percentage of Ki-67-positive cells.

Main Results:

• Turnover indices (TIs) successfully distinguished between NHL categories and subtypes based on the Kiel classification.
• Approximately one-third of high-grade lymphomas were reclassified as low-turnover lymphomas based on TI and Ki-67 analysis.
• Patients with low-turnover lymphomas exhibited significantly longer overall survival compared to those with high-turnover lymphomas.

Conclusions:

• The turnover index (TI) is a valuable parameter for classifying and understanding the kinetics of non-Hodgkin's lymphomas (NHLs).
• TI assessment can be simplified by counting mitotic figures and apoptotic cells, offering a practical diagnostic tool.
• The TI concept aids in interpreting NHL kinetics, distinguishing between cell accumulation and proliferation, and has prognostic implications.