ECP 2023 Abstracts

S324 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 options and poor prognosis. Further research is required for a better understanding of the underlying pathophysiology to implement tar- geted molecular therapy. E-PS-17-002 Stearoyl-CoA desaturase 1 overexpression in temozolomide-resist- ant glioblastoma cell line associates with an epigenetic modification S.M. Alqahtani*, A. Alkhanjaf, A.M. Assiri, A. Abusharib, A. Ibrahim, E. Elagab, A. Shediwah, S. Talballah, S. Samer *Najran University, Saudi Arabia Background & objectives: SCD1 is a key rate-limiting enzyme for lipogenesis. Overexpression of SCD1 has been reported to promote tumorigenesis. Temozolomide (TMZ) is used as a treatment for glio- blastoma patients, however, resistance to TMZ is one of the major clinical challenges. Methods: The U87 glioblastoma cell line was treated with 120 μM of TMZ for four months after testing different concentrations to develop U87-resistant cells (U87-RC). The non-tumour normal human astro- cytes (NNHA) cell line was used as another control. For studying methylation status, genomic DNA was extracted, and methylation was carried out using a OneStep qMethyl Kit according to the manufac- turer’s protocol. Results: There was a significant upregulation of SCD-1 mRNA and protein levels in both U87 and U87-RC, compared to NNHA. Interestingly, there was a significant increase in the expression of SCD1 at the mRNA levels in U87-RC, Compared to U87. Although the mRNA and protein levels of SCD1 in U87 were significantly higher than those of NNHA and up to a greater extent during star- vation on 2% of foetal bovine serum (FBS), there was no change in the level of methylation with or without starvation (10% FBS). However, the levels of methylation of SCD1 were suppressed sig- nificantly in U87-RC. Conclusion: The results conclude that the upregulation of SCD-1 mRNA and protein levels in U87-RC and UR87 are regulated by dif- ferent biological processes. In addition to that, the association between the increased expression levels of SCD1 and methylation suppression in U87-RC may have a role in TMZ resistance. Finally, further studies are needed to reveal detailed relation between SCD1 overexpression and TMZ resistance in astrocytic tumours. Funding: Charity Department at PentaM Co. E-PS-17-003 Extraspinal soft tissue sacrococcygeal myxopapillary ependymoma. Report of a case E. Athanasiou*, E. Michalopoulou-Manoloutsiou, M. bobos, D. Hatzibougias *MicroDiagnostics, Private cyto/histopathology/molecular lab, Greece Background & objectives: Primary extraspinal soft tissue myxopapil- lary ependymoma (MPE) is an exceptionally rare lesion that is mainly located in the subcutaneous sacrococcygeal region. We report a case of a 33-year-old man presenting with a slow growing painful mass on sacrococcygeal region. Methods: Grossly, the tumour had yellowish cut surface, measured 3*2.8*1.8 cm. Microscopically, it was a cellular lesion, containing ovoid cells with only minimal nuclear variation and mitotic activity. There was microcystic areas with cuboidal cells arranged around pools of basophilic myxoid material and also radially around fibrovascular cores with intervening myxoid material. The tumour cells expressed CD99, CD56, S100, GFAP and, focalCKAE1/AE3. Results: The final diagnosis was soft tissue MPE. Subsequently, the patient underwent a wide local surgical resection that confirmed com- plete removal of the tumour. Conclusion: Extraspinal MPE probably arise from extramedullary ependymal rests representing remnants of the coccygeal medullary vestige. The differential diagnosis includes sacrococcygeal teratoma, neurogenic tumour, soft tissue sarcoma, and metastatic carcinoma, and in sacrum and coccyx, tumours such as chordoma and chondro- sarcoma. Immunopositivity of the tumour cells with GFAP helps in confirming the diagnosis of MPE. The treatment of choice is gross total resection. This treatment makes possible a cure without the need for adjuvant therapy. E-PS-17-004 Primary EBV-negative CNS T cell lymphoma in a patient with B cell chronic lymphocytic leukaemia: a case report L. Cardisciani*, M.E. Maracci, L. Di Sciascio, M. Martinoni, C. Tonon, R. Liguori, P.L. Zinzani, E. Sabattini, S. Asioli *School of Anatomic Pathology, Department of Biomedical and Neu- romotor Sciences, University of Bologna, Italy Background & objectives: Peripheral T-cell lymphoma accounts for 2–4% of primary Central Nervous System (CNS) lymphomas, usually present as single mass and involved sites include the fron- tal and temporal lobes, cerebellum, pituitary gland and (rarely) the leptomeninges. Methods: A 57-years-old male patient with a diagnosis of Chronic Lymphatic Leukaemia (CLL) developed persistent headache, fever and seizures. Head-CT and brain-MRI revealed multiple oedematous lesions with contrast enhancement. A stereotaxic biopsy was performed after dexamethasone. 18FDG-PET-CT and CSF analysis were unre- markable, marrow biopsy confirmed mild B-CLL infiltration (<10%). Meanwhile the symptoms worsened and oedema and lesions increased at the MRI. Results: The biopsy showed extensive necrosis and macrophages, with sparse lymphocytes showing prominent angiocentricity, cytologic atypia, medium/large size and moderate nuclear pleomorphism. The phenotype showed T-cell origin (CD3+, CD2+), Tia-1 positivity, high Ki67 and defective expression of CD5, CD7, CD4, CD8; TdT, CD30, ALKc and CD56 were negative. EBV-encoded small RNAs were not detected at in-situ hybridization. Clonal T-cell Receptor Gamma genes rearrangement was detected. Diagnosis was consistent with peripheral T/NK cell lymphoma, better classified as Not Otherwise Specified. The patient was treated with methotrexate, cytarabine and thiotepa but ultimately died 3 months later. Conclusion: The present case fulfils the criteria of primary CNS T/NK cell lymphoma with extensive necrosis and angiocentric growth-pat- tern. The latter features and the cytotoxic double-negative phenotype, in the context of a likely BCLL-related immune-deficiency, could sug- gest a nasal-type subtype. However, the evidence of T-Cell-Receptor rearrangement, absence of EBV integration, CD56 and CD30 negativ- ity favoured a final diagnosis of a NOS subtype. The clinical course of this case was rapidly progressive with very poor prognosis with no effective available treatment protocols. E-PS-17-005 A possible diagnostic pitfall in tumours of pineal gland region in adults: poorly differentiated primary glial tumour with primitive neuroectodermal differentiation T. Čeprnja*, K. Žarković, I. Brnadić, I. Lukić, D.A. Grubišić, A. Jakovčević *University Hospital of Split, Croatia Background & objectives: Pineal region tumours are rare neoplasms, most of which originate from pineal gland parenchyma. Pineal region gliomas arising from glial stroma of pineal gland are even more uncom- mon. We present a case of malignant glioma arising in pineal region.