Background: Based on the World Health Organization (WHO) classification, the distribution of various subtypes of malignant lymphoma (ML) appears to differ by geographical region.
Aims and design: studying the patterns of ML retrospectively in a previously uncharted country (Iraq) and to compare it with patterns observed regionally and worldwide.
Materials and methods: Two hundred and seventy lymphoma patients referred to two major histopathology referral centers in Northern Iraq, were categorized according to the WHO classification, using morphology and appropriate immunohistochemistry.
Results: There were 205 (76%) non-Hodgkin lymphomas (NHL) and 65 (24%) Hodgkin lymphomas (HL). Of the NHL, 91% were B-cell and 9% T-cell. The most common NHL was Diffuse large B-cell lymphoma (DLBCL) which comprised 52.2% of NHL, followed by Burkitt's lymphoma (BL) at 14.6%. The latter were mostly intestinal primaries. While follicular lymphomas (FL) were infrequent constituting 2.9 % of NHL. Extranodal primaries were found in 48.3% of NHL. Hodgkin's lymphoma (HL) included 48% nodular sclerosis (NS) and 37% mixed cellularity (MC). All HL were nodal primaries.
Conclusions: Among NHL, the high frequencies of DLBCL, extra nodal primaries and intestinal BL, and the infrequency of FL in northern Iraq, is similar to reports from nearby countries but differs considerably from the West and Far East, indicating a shared regional Middle East influence on non-Hodgkin lymphoma patterns. In contrast to earlier Iraqi and regional studies on HL, NS has surpassed MC as the most frequent histological subtype in Northern Iraq. This trend probably reflects the increasing urbanization that has taken place in this region.