The Comparison of De Novo Grade 3 Follicular Lymphoma and Transformed Grade 3 Follicular Lymphoma: Own Data

Background. Grade 3 follicular lymphoma (FL) is a heterogenetic group of tumors. The selections of patients with similar characteristics of the tumor process is important for classification 3 grade forms of FL and risk stratification, as well as for the development of new therapeutic approaches. Different morphological, immunohistochemical and cytogenetical characteristics of the tumor result in different clinical forms of the disease. Aim. To describe the clinical, morphological, immunohistochemical and cytogenetical characteristics of grade 3 FL and evaluate their prognostic value for R-CHOP-21 chemotherapy. Materials & Methods. We performed retrospective and prospective analysis of morphological, immunohistochemical and genetical characteristics of 93 primary patients with grade 3 FL (21–78 years, median 53 years, women to men — 1:1.4) admitted to National Medical Hematology Research Center from years 2001 to 2016. Morphological and immunohistochemical assessment of the affected lymph nodes and bone marrow biopsy material was performed. Data obtained from the standard cytogenetic and FISH assessment were compared to identify the BCL2 rearrangement. Results. We proposed an algorithm for differential diagnosis of the 2 types of grade 3 FL: de novo FL (n = 22) and transformed FL (n = 21). De novo grade 3 FL had the immunophenotype of CD10– in 19 (86 %) cases, MUM1++ (monomorphically) in 19 (90 %), and BCL-2 in 5 (22 %). It was characterized by the absence of the BCL2 rearrangement (n = 22, 100 %) and bone marrow involvement (n = 14, 67 %) and/or bone marrow involvement (n = 7, 100 %). Third grade FL transformed from grades 1 or 2 had was CD10+ (n = 19, 90 %), MUM1+ (heterogeneously, n = 16, 76 %) or MUM1– (n = 4, 19 %), BCL-2+ (n = 20, 95 %) and had BCL2 rearrangement (n = 19, 90 %). Small cell bone marrow involvement was observed in 71 % of cases, whereas large cell involvement was seen predominantly in de novo FL (p = 0.06). The analysis showed that 5-year relapse-free survival in patients with grade 3 de novo FL after R-CHOP-21 therapy was 87 % compared to 16 % with transformed FL (p = 0.06) for the median 41 months of follow up. Conclusion. We described the morphological, immunohistochemical and cytogenetical characteristics of grade 3 de novo FL and grade 3 FL, transformed from grades 1 or 2. The described variants show different sensitivity to immunochemotherapy