ECP 2023 Abstracts

S325 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Methods: A 61-year-old female patient with history of breast can- cer presented herself to an outside facility after experiencing periods of confusion, intense headaches and generalized epileptic seizures. MRI was performed, which described a tumour originating from pin- eal gland, with radiomorphological characteristics of pineoblastoma. Patient was admitted to our hospital, and two craniotomies were per- formed with aim of maximal tumour reduction. Results: Two samples of tumour tissue were separately admit- ted for histological examination, both consisting of small tissue fragments. Examination of both samples showed a highly cellular tumour composed of small, blue, round cells with scant eosinophilic cytoplasms, and with numerous mitoses and apoptotic bodies. No necrosis was observed, and microvascular proliferation was seen focally. Immunohistochemicaly, tumour cells were GFAP negative, NSE and synaptophysine positive. No mutations of IDH1 or ATRX were observed, and Ki67 proliferation index was around 40%. On further testing Olig2 staining was positive. Diagnosis of primary high grade glial tumour with primitive neuroectodermal differentia- tion was set, and samples were sent for molecular analysis, which later confirmed the diagnosis. Conclusion: While most cases of pineoblastoma, a WHO grade 4 tumour arising from pineal parenchyma, are described in children and young adults, some cases were reported in older population. As cases of primary glial tumours of this region are very rare, radiomorphological characteristics of high-grade glial tumours can easily be mistaken for pineoblastoma. Similarly, on histological examination, poorly differ- entiated tumours with loss of GFAP expression and neuroectodermal differentiation, could easily be misdiagnosed as pineoblastomas if not taken into consideration. E-PS-17-006 Cerebral amyloid angiopathy and neurodegenerative pathologies: beyond Alzheimer’s disease A. Chaachou Charradi*, I. Burgueño García, M. Riba Barroso, S. Ramón y Cajal Agüeras, A. Rábano Gutiérrez, E. Martínez Sáez *Vall d’Hebron University Hospital, Spain Background & objectives: Cerebral amyloid angiopathy (CAA) is the main cause of intracerebral haemorrhage in normotensive elderly. Its association with Alzheimer’s disease (AD) is known, as they share abnormal deposits of Amyloid-β protein. However, we consider inter- esting to elucidate its frequency outside AD. Methods: We present a cohort of 362 brain donors from two Spanish brain banks, including 71 control patients (absence of clinical diag- nosis of dementia), 203 AD cases (including early-onset (EOAD)) and 59 other neurodegenerative diseases (ND) (Lewy body disease (LBD), amyotrophic lateral sclerosis (ALS), tauopathies). Clinico- pathological data were collected, and the presence of CAA pathology was evaluated. Results: As expected, there was a significant correlation between CAA and AD (88,2% prevalence of CAA within the group). However, CAA was also found in a non-negligible percentage of LBD (57,7%), control cases (31%) and ALS/TDP-43 (26,7%). Conversely, the tauopathies group showed the lowest percentage of CAA (15,8%). Interestingly, there were no statistically significant dif- ferences in CAA affectation between early and late-onset AD, although the percentage is notably higher in EOAD (98%). Regarding the age at exitus, groups were homogeneous and no signifi- cant differences were found between them, being the highest mean age in the AD group (84,26 years) and the lowest mean age in the ALS/ TDP-43 group (61,13 years). Conclusion: In summary, we should keep in mind that, outside AD, CAA can be present, particularly in LBD and even in asymptomatic patients. This is an important finding, as CAA is a major cause of morbidity and mortality, and significant progress has been made in the development of targeted therapies against Amyloid-β protein. Improved knowledge of CAA in non-AD ND could extend these treat- ments to other NDs, as the above mentioned. E-PS-17-007 Secondary diffuse large B-cell lymphoma of the CNS: a case report J.L. Delgado Fernández*, I. Marquina Ibáñez, J. Alfaro Torres, S. Hakim Alonso, J.M. Lazaro Maisanava, N. Martínez Arnau, J. Mar- tínez Castillón, L. Leon, J. Medrano Ruiz, A. Carilla Sanromán *Hospital U. Miguel Servet, Spain Background & objectives: Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin’s lymphoma. Central nervous system (CNS) metastasis of DLBCL are uncommon, ranging from 2% to 25%, and result in an extremely guarded prognosis. Methods: We report a case of a 67-year-old man previously diag- nosed with colonic DLBCL treated with chemotherapy and in com- plete remission for 3 years that presented with language and memoire impairment. An MRI was performed, showing a lesion in the left tem- poral lobe. The patient underwent surgery, performing a left temporal lobe craniotomy with a biopsy/removal of the lesion. Results: Macroscopically, several whitish cylindrical fragments between 0,5 and 0,9 cm in maximum diameter were received. His- tologic study revealed neuroglial tissue infiltrated by loose cells of lymphoid habit. These cells were large, with irregular nuclei and tended to gather around vessels in Virchow-Robin spaces with perivascular cuffs. The cells expressed CD20, CD79a, BCL6, CD10 and MUM1 (focally), with a proliferative index of 70% and were negative for BCl2, CD30 and EMA. Given the clinical history and these histologic and inmunohistochemistry findings, a diagnosis of metastatic DLBCL was made. Conclusion: Metastatic involvement of the CNS by a lymphoprolifera- tive process is uncommon. In those cases, specifically DLBCL, pre- vious history and CD10 are indispensable for differentiate this CNS relapse from a primary CNS-DLBCL. E-PS-17-008 OPN overexpression in psammomatous meningiomas A. Denysenko*, R. Moskalenko *Sumy State University, Ukraine Background & objectives: Meningiomas are the most common pri- mary tumours of the central nervous system. Their calcification is con- troversial and can both facilitate and complicate diagnosis and treat- ment. The work aims to study OPN expression in meningiomas tissue with and without calcification. Methods: The study group included 30 samples of psammomatous meningiomas (group I) and 30 samples of meningiomas (meningothe- lial, fibroblastic) without any signs of biomineralization (group II). We use histological and immunohistochemical methods. We use the anti-OPN antibody (Thermo Fisher Scientific, PA5-34579, dilution 1:300), followed by DAB detection substrate and counterstained with Mayer’s hematoxylin. Results: We can conclude that OPN expression increased in menin- giomas with calcifications (137,19±12,97 cells per 1 mm2) in com- parison to those without them (57,47±9,34 cells per 1 mm2, p<0.001, Student test). Also, we can observe OPN mainly localized in the tissue around the calcifications. Conclusion: We observe a significant difference in OPN expression in the group of meningiomas with calcifications compared to those without signs of biomineralization. Overexpression of OPN in menin- giomas with calcification tissue may be a promising diagnostic marker.