Aga Khan University Hospital, Stadium Road, Karachi
Abstract
Lymphomas are classified as Hodgkin’s and Non-Hodgkin’s lymphomas (HL; NHL); NHL being further subdivided into B, T and Null cell categories on the basis of WHO classification. With a few exceptions worldwide, B-NHL are more common, accounting approximately 80-85% of all cases of NHL compared to T-NHL, which accounts for about 10-15% of all NHL cases. The incidence of NHL has shown a steady increase and attention is being focused on the possible causes of this increase. Epidemiologic studies indicate that environmental factors do play a role in the causation of NHL, such as drugs, pesticides, solvents, hair dyes, viruses (EBV, HTLV-1, Hepatitic C and HIV) and Helicobacter pylori. Hence many different environmental factors of risk acting on large segments of the population can contribute for increase of NHL.