[The results of histological and immunohistological studies of primary biopsies in 400 patients with non-Hodgkin's lymphoma in the North-West region of Russia (according to WHO classification)].

AIM: To determine relative frequency of non-Hodgkin's lymphoma (NHL) variants according to WHO classification categories in the North-West of Russia by the data of the local pathomorphological department. MATERIAL AND METHODS: Four hundred consecutive untreated patients with NHL were diagnosed according to the WHO classification between January 2000 and October 2003 in the Regional Bureau of Pathology, St-Petersburg. The patients' age, gender, location of the biopsied tumor focus were considered. The immunohistochemical study was performed by the paraffin section-immunoperoxidase method. Cases of plasma cell myeloma and bone marrow trephine biopsy diagnosed neoplasms were excluded, the rest series of 377 cases was compared to other regional world series. RESULTS: B-cell lymphomas accounted for 79.6% and T-cell type for 20.4% of 377 NHL cases. 33.2% cases were different histological variants of diffuse large B-cell lymphoma, 17.0% were B-cell small lymphocytic lymphomas, 11.0%--follicular lymphomas, 4.5%--mantle cell lymphomas, 2.1%--extranodal marginal zone B-cell lymphomas (MALT-type), 1.9%--primary B-cell mediastinal lymphomas. Peripheral T-cell lymphomas, unspecified and anaplastic large T/null cell lymphomas were diagnosed in 6.4 and 4.2% of 377 cases, respectively. Other lymphoma diagnoses comprised 19.7%. CONCLUSION: Diffuse large B-cell lymphomas and B-cell small lymphocytic lymphomas are prevalent among B-cell neoplasms. Follicular lymphomas and mantle cell lymphomas are less common in the North-West of Russia compared to Europe and USA. The relative frequency of extranodal marginal zone B-cell lymphomas (MALT-type) is lower and anaplastic large T/null cell lymphomas is higher than these in International Lymphoma Study Group, Taiwan and Japan series. This study provides evidence that the distribution pattern of non-Hodgkin's lymphoma subtypes in the North-West of Russia shows significant differences with those from the rest of the world.