PD1 distribution pattern, regardless of the cell origin, is an independent microenvironmental prognostic factor for progression-free survival in follicular lymphoma.

Follicular lymphoma (FL) is a well-studied microenvironment-dependent hematological malignancy, but the crosstalk between various involved cell subtypes is still not fully understood. Recent promising results of immunotherapy in recurrent FL warrant the need for an in-depth analysis of the expression and role of immune system-related proteins in the FL microenvironment. Seventy-one patients with FL and available diagnostic paraffin blocks were enrolled in the retrospective analysis. Histopathological diagnoses were revised according to the World Health Organization recommendations. Patients were either observed (watch and wait/W&W group) or immediately treated with chemo(immuno)therapy regimens according to their clinical status. Immunohistochemical assessment of PD1, PDL1, CD4, CD8, CD163, CD68-KP1, CD68-PGM1 was performed. The scoring methods included both semi-quantitative estimation of positive cells and architectural pattern distribution. The differences between PD1 staining distribution and intensity were classified as intra/perifollicular vs. interfollicular/diffuse cells and presented bright vs. dim immunoreactivity, respectively. No statistically significant differences in the density distribution of the immunohistochemical stainings were found between W&W and chemo(immuno)therapy groups. Interfollicular/diffuse pattern of PD1 expression had significantly decreased progression-free survival when analyzing the whole cohort and patients on chemo(immuno)therapy (p = 0.014 and p = 0.07, respectively). The high dependence was not significant in the W&W group. PD1 positivity of cells did not correlate with CD4 or CD8 immunophenotype. Morphologically FL neoplastic cells were entirely PDL1 negative, but granular and membranous staining was detected in the FL microenvironment. In line with previous studies, PD1/PDL1 expression was predominantly localized in the FL microenvironment, indicating that FL cells might not be the direct target for anti-PDL1 therapy. However, we show that the localization of PD1 expression could be a viable progression-free survival biomarker for FL.

EZH2 Expression in Follicular Lymphoma Is Variable and Independent from the Progression of Disease Within 24 Months of First Treatment.

BACKGROUND/AIM: Follicular lymphoma (FL) relapse within 24 months of the first immunochemotherapy (POD24) indicates more precisely poor overall survival and high risk of death. The aim of the study was to assess the potential value of POD24 in FL and describe the enhancer of zeste homolog 2 (EZH2) expression profile, in correlation with clinical/histopathological/immunophenotypical characteristics. MATERIALS AND METHODS: This retrospective single-center study included 75 patients with FL treated under watch and wait (W&W) and immunochemotherapy regimens. All cases were immunohistochemically assessed: assays were performed for EZH2, CD10, BCL6, BCL2, MUM1, MYC and p53. RESULTS: POD24 was independent of clinical/histopathological/immunohistochemical features and separated patients with inferior outcomes. EZH2 high expression was observed in high/low grade and follicular/diffuse FL patterns. BCL2-negative (p=0.042) and MUM1 (p=0.039), MYC (p<0.001), p53 (p<0.001) - positive cases had significantly higher EZH2 expression. CONCLUSION: POD24 is currently the most useful tool for the identification of poor outlook patients. EZH2 is crucial in FL biology, but the value of its protein expression is limited as a prognostic factor.

Significance of CD10 protein expression in the diagnostics of follicular lymphoma: A comparison of conventional immunohistochemistry with flow cytometry supported by the establishment of BCL2 and BCL6 rearrangements.

INTRODUCTION: Histopathological examination and immunohistochemistry (IHC) with a crucial role of CD10 expression remain a standard diagnostic tool in follicular lymphoma (FL). The results of IHC CD10 detection with different primary antibodies are not fully reproducible, but some reports show that flow cytometry (FCM) can be a reliable method of CD10 identification. METHODS: The aim of the study was to compare results of CD10 expression in FL by IHC and FCM including immunophenotypic features in the context of the BCL2 and BCL6 alterations. RESULTS: Out of 76 histopathologically diagnosed FL, a group of 25 cases had simultaneously FCM. Immunohistochemically 77.6% of cases were CD10-positive with comparable and reproducible results to FCM. Differences between the FCM expression of CD5/CD10/CD11c/CD25/CD43 and BCL2 overexpression (BCL2(+)higher ) correlated with the BCL2 and BCL6 rearrangements (R) status. Lack of CD10 expression corresponded with the absence of BCL2R and higher MUM1 expression by IHC results but had no clinical impact on the long-time outcomes. CONCLUSIONS: Immunohistochemistry staining is a comparable method to FCM assessment in the evaluation of CD10 expression and diagnosis of FL. Fine-needle aspiration biopsy/FCM (FNAB/FCM) could be a useful tool for verifying FL diagnosis and CD10 detection. Despite its heterogeneity, FL has a characteristic immunophenotype. BCL2R and BCL6R FL cases differ mainly in levels of BCL2 and CD10 with CD43 co-expression; BCL2(+)higher by FCM correlates with BCL2R. Moreover, FNAB plays an important role in material provision for supportive karyotyping and BCL2R, BCL6R assessed by FISH.