ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 and evolutionary potential of these lethal tumours of the central nervous system. Funding: This work was supported by “Ovidius” University of Con- stanta through the grant no. 3/21.10.2021. E-PS-17-009 Accuracy of anti-PHH3 antibody in meningioma grading N. Mansouri*, M. Ben Thayer, F. Gargouri, K. Takout, R. Aouadi, K. Tlili, I. Msakni, B. Laabidi *Department of Pathology, Military Hospital of Tunis, Tunisia Background & objectives: Proliferative potential is an important criteria for meningioma grading. Phosphohistone-H3 has been suggested as a valid proliferative marker in many tumours. We aim to evaluate the efficiency of anti-PHH3 antibody as a grading tool for meningiomas. Methods: A retrospective study on a series of 40 meningiomas diagnosed from March 2020 to April 2021 at the Pathology Depart- ment of the Military Hospital of Tunis was performed. We com- pared grade variability according to the mitotic count on H&E stained slides and on PHH3 stained slides. Results: A highly significant correlation was found between mitotic count on PHH3 stained slides (PHH3-MI) and mitotic count on H&E stained slides (H&E-MI). PHH3-MI was higher than H&E-MI in 47.5% cases. A significantly higher sensitivity in the PHH3 counting method was reported in our study. It resulted in an overall upgrading rate of 22,5%; six grade 1 meningiomas upgraded to grade 2, and two grade 2 cases upgraded to grade 3. Conclusion: Our study findings, conforming to the literature, revealed that PHH3-MI is more reliable and accurate in mitotic figures counting in meningiomas than conventional MI. It exhibited a high sensitivity in tumour grading, reported by an upgrade within 22,5% of the cases. Therefore, it might be used as a reliable tool for meningiomas’ grading. Nonetheless, larger studies are obviously needed to obtain a definite conclusion on whether this method should replace the conventional H&E-based MI-method for meningioma grading. E-PS-17-010 A case of type 2 neurofibromatosis M. Filip*, C. Socoliuc, A. Bastian, M. Craciun, D. Raduta, E. Ignat *Colentina Clinical Hospital, Romania Background & objectives: Type 2 neurofibromatosis (NF2) is an autosomal dominant syndrome that primarily affects the central and peripheral nervous system, characterized by neoplastic and hamartoma- tous proliferations of Schwann cells, meningothelial cells, and glia. Methods: We report a 27 years old female, showing multiple tumours in the posterior cranial fossa, having a history of multiple meningiomas and one ependymoma. Clinically, the patient complained of vertigo, headache, balance disor- ders, bilateral hearing loss. The clinico-radiological diagnosis of mul- tiple intracranial meningiomas including one with petroclival location, and one with transverse sinus insertion has been established. Results: Transverse sinus tumour was confirmed microscopically and immunohistochemically as a fibrous meningioma, and showed strong positivity for EMA, Vimentin and PR, with increased ki67 index (6% in hotspot), that can be associated with an aggressive biological behaviour. Petroclival tumour proved to be a Schwannoma, microscopically showing a biphasic pattern with Antoni A and Antoni B zones, immunohistochemically showing strong positivity for S100 and negativity for EMA, PR and BCL2. Given the previous and current morphopathological diagnoses of multiple meningiomas, an ependymoma and a schwannoma, the criteria (NIH / Manchester) for the classification of NF2 were met. Genetic testing and counselling for NF2 were recommended. Conclusion: In patients with NF2 it was acknowledged an increased fre- quency of high-grade meningiomas, making it important to distinguish between a meningioma and a schwannoma, the histology and immunohis- tochemistry being useful tools when there is no family history. The morbidity of NF2 patients is significant and the clinical mani- festations can vary from progressive deafness due to vestibular schwannomas, other central nervous system deficits and craniospi- nal neuropathies (including blindness) from multiple meningiomas. For these reasons, an accurate and early diagnosis is essential. E-PS-17-011 Supratentorial ependymoma, ZFTA fusion-positive: report of a new entity M. Mellouli*, F. Kolsi, I. Saguem, O. Boudawara, L. Ayadi, T. Boudawara, S. Makni *Department of Pathology, Habib Bourguiba University Hospital, Sfax, Tunisia Background & objectives: In the 5th edition (2021) of the WHO classification of CNS tumours (WHO CNS5), Ependymomas should be classified according to a combination of histopathological and molecu- lar features as well as anatomic site (supratentorial, posterior fossa and spinal). Methods: We present a case of supratentorial ependymoma (SE), ZFTA fusion-positive (SEZFTAF) to describe the clinicopathological features and molecular alterations of this rare new entity. A 5-year-old girl, with no medi- cal background, was presented to neurosurgery department for seizure and a month-long history of headache and vomiting. On examination she was conscious and oriented to time and place. Results: MRI demonstrated a right frontal solidocystic mass measuring 50x44x35mm. The tumour showed strong and inhomogeneous enhancement in their solid components after intravenous gadolinium injection. The patient underwent gross total resection of the lesion through right frontal craniotomy. On histological examination, the lesion was well demarcated from adjacent brain. It was composed of cells characterized mainly by round uniform nuclei with speckled chromatin and poorly defined fibrillary cytoplasm. Mitotic activity was significant with the presence of vascular proliferation and some necrotic changes. In immunohistochemical study, tumour cells were positive for GFAP and EMA. We noted a nuclear accumulation of p65 porotein. The tumour was graded 3 according to the WHO CNS5. Conclusion: Most of the SE ZFTAFP tumours arise in the parietal or frontal lobe as in our case. These tumours affect primarily children. They Show varying degrees of anaplasia and have been regarded as WHO CNS5 grade 2 or 3 on this basis. The term “anaplastic epend- ymoma” is no longer listed. SE ZFTAFP show nuclear accumulation of p65 protein and cytoplasmic expression of L1CAM. Immunoreactivity for p65 has been found to have a slightly higher specificity. E-PS-17-012 Glioblastoma associated with a primitive neuroectodermal tumour of the brain as a poorly differentiated dimorphic malignant tumour in a 38-year-old man. A rare case report M. Mnikhovich, D. Pastukhova, T. Bezuglova, A. Romanov*, S. Snegur, L. Erofeeva, I. Shiripenko, O. Sidorova *Central Pathology Laboratory, Research Institute of Human Mor- phology, Russia S316