ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: The risk of recurrence and metastasis of solitary fibrous tumours is greatly dependent of proliferation. We aimed to determine the prognostic significance of Ki67 and PHH3 evaluated by digital image analysis in a cohort of 86 menin- geal solitary fibrous tumours. Methods: We compared eye-balling estimation, manual count- ing, and standardized digital image analysis using QuPath soft- ware to evaluate cellularity and proliferation based on Ki67 and PHH3, with correlation with survival in a retrospective cohort of 86 meningeal solitary fibrous tumours. The concordance between the methods was calculated and the processing time was compared. Results: Evaluation of proliferation by digital image analysis with Ki67≥0.05 or PHH3≥0.0006 cut-off was significantly associated with worse PFS and OS in univariate and multivariate analyses, with a significantly shorter processing time for digital image analysis. Manual counting and digital image analysis were highly correlated, with a concordance correlation coefficient of 0.973 (95% CI: 0.061-0.981) for Ki67 and 0,810 (95% CI: 0.725-0.867) for PHH3. Eye-balling estimation showed less correlation with other methods. Conclusion: Digital image analysis is a fast and accurate method for evaluating proliferation markers. Using this method, Ki67 ≥0.05 and PHH3≥0.0006 have a negative impact on PFS and OS in univariate and multivariate analyses. OFP-13-006 Morphological analysis with morphometry of meningioma calcifications A. Denysenko*, R. Moskalenko *Sumy State University, Ukraine Background & objectives: Meningiomas are the most common non-glial tumours of the central nervous system. Differential diagnosis of meningiomas is a challenging problem due to their location. The work aims to study the morphology, structure, and phase analysis of meningiomas’ psammoma bodies (PB). Methods: The study group included 30 patients with calcified meningiomas. We use histological techniques, transmission and scanning electron microscopy with microanalysis. We captured all photos with the digital visualisation system on Zeiss Primo Star microscope with digital camera ZEISS Axiocam ERc 5s and software package “Zen 2.0”. We performed the statistical analysis of the results using GraphPad Prism 7.04. Results: All meningioma samples contained PB in the fibrous tissue of the tumour. According to the histological examination and SEM results, PB had a layered structure. They were often in the form of fragments and fragments that preserved the original structure. The number of PB in meningioma tissue varied from one to hundreds of units. In our study, the size of the PB ranged from 20.01 to 197.02 μm. We can generally divide PB by dimensional characteristics (larger formation diameter) into three groups: large (more than 100 μm), medium (70-100 μm) and small (less than 69 μm). Conclusion: PB is a promising diagnostic marker for the prognosis of dura mater tumours, which doctors and scientists can use in radiologi- cal and histological methods. According to morphometry results, we can divide PB into three groups by size - large, medium and small. OFP-13-007 Thalamic diffuse midline glioma, a series of cases from a single cancer centre S. Al Sharie, D. Abu Laban, S. Ghnaimat, M. Al- Hussaini* *King Hussien Cancer Center, Jordan Background & objectives: Diffuse midline glioma (DMG) of thalamus is rare, as thalamic tumours, in general, represent 1% of all intracranial neoplasms. It is associated with aggressive behav- iours and poor prognosis. Recently, DMGs are characterized by the presence of an H3K27M gene mutation. Methods: Eighteen thalamic DMGs are reviewed, including the age, gender, and laterality. Immunostains for GFAP, H3 K27M, and H3 K27me, IDH1 (R132H), P53. The outcome of the cases is reported. Results: There were 11 males. The average age is 34 years (median 27.5). All cases were positive for GFAP. Eight cases were mutant for H3 K27M, all with loss of H3 K27me staining. In addition, a single case showed loss of H3 K27me immunostain in the pres- ence of non-mutant H3K27M. There were 8 P53-mutant cases. All cases were IDH1 (R132H) wildtype. Of interest, there were 3 cases diagnosed as pilocytic astrocytoma, including a case that was H3 K27M mutant. Of those with available survival data, 10 were dead, including 4 cases of mutant H3 K27M and a single case of wildtype H3 K27M, but with loss of H3 K27me. Conclusion: Around 50% of the cases are consistent with the diagnosis of DMG where H3 K27M is altered. However, there remains a number of cases with dismal outcomes that were non- H3 K27M altered. These should be further tested for potential other mutations. OFP-13-008 Histone H3 trimethylated in lysine 27 (H3K27me3) immuno- histochemical loss predicts shorter progression-free survival in intracranial meningiomas treated with radiosurgery P.C. Rizzo*, S. Ammendola, M. Longhi, E. Zivelonghi, S. Pedron, G. Pinna, F. Sala, A. Nicolato, A. Scarpa, V. Barresi *Department of Diagnostic and Public Health, University of Verona, Italy Background & objectives: Loss of H3K27me3 has been recently associated with an increased risk of recurrence in meningiomas. In the current study, we aim to investigate whether H327 trimethylation status can predict the response of meningiomas to stereotactic radiosurgery. Methods: H3K27me3 expression was evaluated by immunohisto- chemistry in 39 surgically resected, treatment-naive intra-cranial meningiomas, treated with stereotactic radiosurgery (SRS) for a residue or at recurrence. The immunohistochemical results were correlated with tumour recurrence and recurrence-free survival (RFS) after SRS. Results: Seven meningiomas had H3K27me3 loss, 27 retained H3K27me3 expression and five has inconclusive immunostaining. The immunohistochemical loss of H3K27me3 was significantly associated with tumour recurrence (P= 0.0143) and with shorter RFS (P=0.0036) after SRS. Conclusion: Our findings suggest that the absence of H3K27me3 in neoplastic cells may concur to a weaker response to stereotactic radiosurgery in meningiomas. OFP-13-009 Concerted deposition of vascular basal membrane proteins laminin beta 1 and 2 supports neo-angiogenesis and contributes to vascular permeability S. Bannykh*, K. Bannykh *Cedars-Sinai Medical Center, USA Background & objectives: Expression profiling studies of glio- blastomas (GBM) showed striking over-expression of laminin beta 1 (LAMB1) isoform with concomitant loss of LAMB2. Inhibition of LAMB1 expression by nanoconjugates suppresses S54