ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 C. Faria*, F. Ramalhosa, J. Gama, J. Madeira, B. Sepodes, C. Courelas, O. Rebelo *Pathology Unit, Hospitais da Universidade de Coimbra, Centro Hospitalar e Universitário de Coimbra, Portugal Background & objectives: Pleomorphic xanthoastrocytoma is a circumscribed astrocytic glioma that generally occur supratentori- ally, more frequently in young patients. BRAF V600E mutation and homozygous CDKN2A and/or CDKN2B deletion are common altera- tions in this entity that also presents a DNA methylation profile. Methods: We report the case of a 19-year-old woman that pre- sented headache, nausea and visual hallucinations. Imagologi- cal study revealed an expansive lesion in the left temporal lobe with hyperintense signal on T2-weighted image and postcontrast enhancement on MRI. Adjacent oedema was slightly pronounced. Surgical ressection was performed. Results: Histopathological examination showed a neoplasia with solid and non-invasive growth pattern, predominantly composed of multinucleated giant cells with pleomorphic nuclei, frequent intranuclear pseudoinclusions and prominent nucleoli. There were also large epithelioid cells with eosinophilic and dense cytoplasm, hyperchromatic central nuclei and astrocytes filled with lipid droplets resembling xanthomatous cells. Ocasionally rhabdoid cells with eccentric nuclei and eosinophilic granular bodies were observed. Mitotic activity represented 13 mitoses/10 HPF. A moderate lymphocytic perivascular infiltrate and reticulin deposition were present. Immunohistochemistry revealed diffuse positivity for vimentin and focal for GFAP, OLIGO2, MAP2, EMA, CD34, neurofilament and synaptophysin. Ki67 was 10-15%. BRAF V600E was negative at immunohistochemistry and by sequencing analysis. Conclusion: The diagnosis was pleomorphic xanthoastrocytoma (PXA), grade 3 and BRAF wildtype. Although with better progno- sis than specific gliomas, especially at young age, PXA frequently recurs. A high mitotic activity and necrosis have also been associ- ated with worse prognosis. About 80% of PXAs harbour BRAF V600E mutation but this finding is not present in our case. How- ever, the DNA methylome profile confirmed the diagnosis. The patient has been submitted to radiotherapy, followed by chemotherapy, revealing a better clinical outcome. E-PS-17-003 One year of neuropathology during the pandemic - a review of central nervous system tumours diagnosed at the Bagdasar- Arseni Hospital, Bucharest during 2021 D. Pasov*, C. Cocosila, M. Lisievici *Bagdasar-Arseni Clinical Hospital, Romania Background & objectives: 2021 was another year straining the health- care system in Romania, which was also reflected in the pathology field. We have reviewed all the central nervous system (CNS) tumours diagnosed by our team throughout this year. Methods: All tumour cases have been examined by light micros- copy using the standard hematoxylin and eosin stain and diagnosed according to the WHO revised 4th edition classification (2016). Several of these tumours were examined during intraoperative con- sultation as both frozen sections and squash/smear technique using the toluidine blue stain. For the sake of this study, traumatic and inflammatory lesions were excluded. Results: A total of 749 CNS tumours were diagnosed by our department in 2021, consisting of 569 primary and 180 metastatic lesions. 605 tumours were located to the brain while 144 were spinal. Only 50 of the spinal tumours were primary. The most com- mon brain tumours encountered were diffuse gliomas consisting of 158 cases, out of which 126 were diagnosed as glioblastomas. Other glioma types, as well as glioneuronal tumours were rare, consisting of 34 cases. Meningiomas of both brain and spine were more frequent accounting to 156 and 13 cases respectively. Pitui- tary adenomas, embryonal tumours and schwannomas were also significantly encountered. 449 intraoperative consultations (frozen sections and squash/smear) were performed. Conclusion: While tumour diversity encountered throughout the year is consistent with global epidemiology, a few variations were noticed. These were likely influenced by the temporary restric- tions and availability of ICU beds during the pandemic waves. While surgery for metastatic lesions remained consistent, primary tumours, especially lower grade ones, were affected. A decrease of paediatric cases was also observed. About 60% of diagnosed tumours benefitted from intraoperative consultation. E-PS-17-004 Simple subependymal cyst derived from the floor of the third ventricle: a case report of an extremely rare midbrain location N. Flaris, C. Gouta*, V. Tsitouras, P. Monioudis, I. Venizelos *Department of Histopathology, Hippokration General Hospital of Thessaloniki, Greece Background & objectives: Ependymal cysts are rare benign lesions that occur mostly in the lateral ventricles or less commonly into the subarachnoid space and the brain parenchyma. The third ventricle is a very rare location, let alone the midbrain and the periaqueduct area. Methods: We report the case of a 3-year-old male who presented at the emergency department with symptoms of acute hydrocepha- lus. Brain imaging tests revealed a dilation of the third and lateral ventricles and the patient underwent endoscopic brain surgery. A thin-wall, transparent cystic lesion was found to originate from the floor of the third ventricle obstructing the aqueduct of Sylvius. Results: A part of the cystic wall of 0.5 cm in maximum length was biopsied and sent for pathological examination and immunohistochemical analysis. Microscopically the tissue was composed of multiple layers of a three-structured membrane. A thin aggregate of collagen fibres was lined on one side with a zone of glioependymal cells and on the other with a single stratum of flattened cells of unknown origin. Immunohistochemical markers S100 and vimentin were positive on both types of cells, while EMA, GFAP and CK7 were positive only on ependymal zone. General proliferation marker ki67 showed positivity for circa 3% of glial cells. Consequently, the diagnosis of a simple subependymal cyst was established. Conclusion: To our knowledge, until now there have been reported only 2 cases of midbrain ependymal cysts, both of which occurred in adult patients. Cysts recognized in the third ventricle are usually colloid rather than ependymal. Notably, there is a gap in literature with regards to detailed histological description and immunohistochemistry of benign ependymal lesions. Our case report contributes to medical knowledge presenting an extremely rare entity and posing questions about the cytological features, origin and type of lining cells involved. E-PS-17-005 Anatomical distribution of cancer stem cells between enhancing nodule and FLAIR hyperintensity in supratentorial glioblas- toma: time to recalibrate the surgical target? G. Broggi*, R. Altieri, F. Certo, G. Barbagallo, R. Caltabiano *Department of Medical and Surgical Sciences and Advanced Technologies "G.F. Ingrassia", Anatomic Pathology, University of Catania, Italy S314