Correlation of Ki 67 proliferative index with clinical and pathological features on tissue sections of non Hodgkins lymphoma by immunostaining

Objectives: To assess Ki 67 proliferative index (PI) in tissue sections, with relation to grade and clinical parameters associated with non Hodgkin s lymphoma in Pakistani population. Methods: All cases of non Hodgkin s lymphoma, diagnosed at histopathology section of Dow Diagnostic research and reference laboratory from October 2008 to June 2010, were included for this cross sectional study. Immunohistochemical study using monoclonal antibody MIB 1, Dako, Denmark against Ki 67 antigen was carried out on paraffin embedded tissue blocks of 62 patients. Ki 67 PI, with cutoff 45% was assessed in relation to specific phenotype, age, gender, site of origin and B symptoms. Mean Ki 67 PI was also calculated considering specific phenotype according to WHO classification. Results: Out of 62 patients, Ki 67 PI 45% was noted in 39 (62.9%) cases, whereas, in 23 (37%) cases the PI was 45%. The mean Ki 67 PI was highest in Burkitt s lymphoma. Furthermore Ki 67 PI 45% was seen in 21/25 (84%) cases with extra nodal involvement and 24/29 (82.7%) cases with B symptoms. Conclusion: Mean Ki 67 PI can discriminate the indolent versus aggressive behaviour of disease. In the study population significant association of high Ki 67 PI 45% was found in relation to B symptoms and site of involvement, in terms of extra nodal origin, for non Hodgkin s lymphoma. These correlations demonstrate the significant role of high Ki 67 PI, to establish the proliferative activity of tumour as prognostic index marker along with clinical parameters at the time of diagnosis.