Introduction: Non-Hodgkin´s lymphomas (NHLs) are heterogeneous group of malignant lymphoproliferative disorders. Study objectives: This was a retrospective study aimed to classify NHLs into B cell and T cell types; in addition to demonstrate the histological patterns and correlate it with gender, age and site of the biopsy.

Methods: The study was conducted in Histopathology Department, National Heath Laboratory, during the period 2007-2010. Formalin fixed paraffin wax embedded tissue blocks which were diagnosed as NHLs by routine Haematoxylin and Eosin (H&E) stain during the period 2000-2008 were used. Haematoxylin and Eosin (H&E) stain were done. Immunohistochemistry stains performed according to Dako cytomation protocol 2007. Lymphoid markers which were used in this study are CD45 (LCA), CD20 (B cell marker), CD3 (T cell marker), CD15 and CD 30. Epithelial marker which was used is CK MNF116. The total number of samples collected was 66; two of them were excluded because of poor processing. Another two specimens were excluded because they are non-reactive with lymphoid markers. The remaining 62 specimens were confirmed to be NHLs and classified into B cell and T cell types.

Results: The study showed that B cell NHLs represented 87.1% while T cell NHLs were 12.9%. The Male: Female ratio was 1.6:1. The major affected age group was (47-67) years (38.1% of all specimens). The most frequent histological grade was intermediate grade NHLs (27% of all specimens). The most common site of NHLs in this study is the lymph node (40% of all specimens) followed by stomach (19.4%).

Conclusion: Extranodal locations are the most common sites affected with T cell NHLs. In conclusion; this study confirmed the fundamental role of immunohistochemistry in diagnosis and classification of NHLs.