Complex diagnosis of follicular lymphomas

Abstract

In the Western world the second most common type of non-Hodgkin's lymphomas is follicular lymphoma (FL) comprising 30-35% of all cases. According to the data of the National Cancer Registry and our institute, this ratio is lower in Hungary and is about 15-20%, but the occurrence shows an increasing tendency. Our aim was to survey and revise FLs that had been diagnosed at the National Institute of Oncology between 1990-1995. We studied the diagnostic relevance of histology, immunohistochemistry and the detection of immunoglobulin heavy chain (IgH) and bcl-2 gene rearrangements. We surveyed 53 cases that were previously diagnosed as follicular or centrocytic, centroblastic lymphoma. Following histological re-examination, immunohistochemistry (CD20, CD3, bcl-2, CD10, bcl-6, CD5, p53, cyclin D1 and Ki-67) was performed on each case. We also studied the IgH and bcl-2 (major breakpoint region=MBR) gene rearrangement on paraffin embedded samples with conventional PCR methods. The classification was made according to the new WHO classification. After the revision of the 53 cases we found 37 follicular, 11 diffuse large B-cell, 1 mantle cell and 1 marginal zone lymphomas, 1 nodular lymphocyte predominant Hodgkin's lymphoma and 2 follicular hyperplasias. The grade of the FLs correlated with the expression of different antigens. CD10, bcl-2 expression and the proliferation index with Ki-67 showed good correlation with the grade of FLs. We could detect bcl-2 gene rearrangement in 55% of the FLs. Considering the diagnostic relevance of the different methods we can conclude that histology alone is not sufficient to make a correct diagnosis. Ninety percent of our cases were solvable with the help of immunohistochemistry and in 10% of the cases the diagnosis was partly based on the molecular pathological results.