Distribution of Ki67 Proliferative Indices among WHO Subtypes of Non-Hodgkin’s Lymphoma: Association with other Clinical Parameters

Background: Non-hodgkin lymphoma (NHL) is a diverse group of disease encompassing divergent tumortypes with contrasting clinical behaviors. We aimed to evaluate the usefulness of Ki67 index in segregatingindolent from aggressive NHL and its association with clinical parameters. Materials and
Methods: Duringa study period of 4.5 years, a total of 215 cases of lymphomas were diagnosed among of which 172 cases wereNHL. Ki67 immunohistochemical staining was performed by the DAKO envision method. Average proportion oftumor cells stained was calculated to determine the proliferative index.
Results: The mean age at diagnosis was46.2 years +19.8 (3-81) with a male to female ratio of 1.5:1. Mean Ki67 index for indolent NHL included 23%for small cell, 25% for mantle cell, 28.5% for marginal zone and 34.6% for follicular lymphoma. On the otherhand, mean Ki67 index for aggressive lymphomas were 66.4%, 66.9%, 80.3%, 83.3% and 94.4% for diffuselarge B cell, T cell (NOS), anaplastic large cell, lymphoblastic and burkitts lymphoma respectively. No significantcorrelation was found between Ki67 index and other clinical parameters like age and extra nodal involvement.
Conclusions: Ki67 index is a valuable IHC marker to distinguish indolent from aggressive lymphomas especiallyin small needle biopsies where exact typing may not be possible.