Subtype distribution of lymphomas in northwestern Iran: a retrospective analysis of 659 cases according to World Health Organization classification

BACKGROUND: The distribution of lymphoma subtypes differs strikingly by geographic variations. However, there is limited information on this research in northern Iran. This study aims to evaluate the incidence, subtype, age, sex, and extranodal distribution of lymphomas diagnosed according to the latest WHO classification in a large referral center in northwest Iran. METHODS: In a retrospective study, the medical records of all patients with a diagnosis of lymphoma made between 2018 and 2021 were retrieved from the pathology archive of Imam Reza Medical Center, Tabriz. Lymphoma diagnosis was also made based on the appreciation of morphologic and immunophenotypic features and genetic characteristics in the context of clinical presentation. RESULTS: This study includes a total of 659 patients with lymphoma diagnosed from 2018 to 2021. The number of lymphoma patients were increased each year, with 51 (7.7%), 96 (14.6%), 244 (40.7%), and 268 (40.7%) reported from 2018 to 2021, respectively. 59% of the patients were men. The participants’ mean age was 50.5 ± 19.8 years, while the mean age at diagnosis was 49.3 ± 19.6 years. 2.1% were precursor lymphoid neoplasm, 61.6% were mature B cell neoplasm, 8.8% were mature T cell neoplasm, and 27.5% were Hodgkin lymphoma. The most prevalent subtype of mature B-cell lymphoma was DLBCL (55.1%), followed by SLL (18.7%). Extranodal involvement was seen in 40.5% of all cases. CONCLUSION: The subtype distribution of lymphomas in northwest Iran is reported and compared with studies all over the world and inside Iran.