Abstract
Actuality: FL3 is a heterogeneous group of follicular lymphomas. Detailed morphological, immunophenotypic and genetic characteristics of FL3 allow to explain clinical heterogeneity of the disease and to develop differentiated therapeutic approaches.
Aim: to characterize clinical, morphological, immunohistochemical (IHC) and genetic features of follicular lymphoma (FL) grade 3 and assess their prognostic value in patients treated with R-CHOP-21.
Materials and Methods: In this retrospective and prospective study, 93 primary patients with FL3 (median age 53 years, range 21 - 78 years, f:m=1:1,4) observed in «National Research Center for Hematology» in Moscow, Russian Federation (2001-2016), were included. Morphological and IHC studies of the lymph nodes and corresponding bone marrow trephines obtained prior to therapy have been carried out. Standard cytogenetics or FISH for BCL-2 have been performed.
Results: Two variants of the disease were identified: de novo FL (n=22) and transformed FL (tFL) - as a result of histological transformation of low grade follicular lymphoma (n=21). De novo FL3 was characterized by CD10 negativity (86%), MUM1 positivity (90%, with strong monotonous staining), absence of BCL-2 rearrangement (100%), although BCL-2 was found positive in 78% of cases. Bone marrow involvement in cases of de novo FL3 was rare (33%), and in all positive cases - with plenty of large lymphoid cells (centroblasts). tFL3 was positive for CD10 (90%), BCL-2 (95%) and carried rearrangements of BCL-2 in 90%. MUM1 was positive in 76% (heterogeneous staining) and negative in 19%. Bone marrow involvement was documented in 67 %, in most cases with predominance of small lymphoid cells - centrocytes (71%). These data were included in the algorithm for differential diagnosis of two variants of FL3. There was no correlation between the 2 variants of FL3 (de novo or transformed) and grades (3A, 3B or 3A+B) (p=0,11). 26 (60 %) patients from the whole group were treated with R-CHOP-21. The 5-year relapse-free survival of pts with de novo FL3 was 87% compared to 16% for pts with tFL3 (p=0,06), Me=41 months (Figure 1).
Conclusion: Two variants of FL3 are described: de novo FL and tFL, which are characterized by different morphological, IHC and genetic features and have various sensitivity to immunochemotherapy.
No relevant conflicts of interest to declare.
