ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 well-circumscribed solid/cystic tumour, with peduncle invasion and normal extension studies. An endoscopic surgical cyst fenestration and Monroe liberation was performed, together with an endoscopic biopsy for diagnosis. Results: Paraffin sections stained with haematoxylin-eosin dem- onstrated a moderately cell-dense neoplasm with piloid astrocytic histological features presenting Rosenthal fibres. Vascular hyper- trophy with glomeruloid proliferation and high mitotic activity (9 mitosis/10 HPF), were observed. Immunohistochemistry revealed loss of ATRX expression in 90% of neoplastic cells with positive staining for Olig2, PGFA and H3K27me3, and negative staining for LIN-28A, H3K27M, p53 and IDH1, with a ki67 proliferation index of 30%. The methylation class was of diffuse leptomeningeal glioneuronal tumour (DLGNT) with a concordance score of 0.57. For further analysis, next generation sequencing (NGS) was performed, demonstrating ATRX mutation; CDKN2A/B deletion, codeletion of 1p/19q; and absence of KIAA1549-BRAF fusion, BRAFV600E and IDH mutation. Conclusion: Histopathological features of high-grade astrocytoma with loss of nuclear ATRX expression, suggested HGAP. Consid- ering the low score value of DLGNT methylation class and the close molecular segregation described in both entities, we extend the study through NGS. This approach enabled us to confirm the presence of a mutation in ATRX and the deletion of CDKN2A/B, endorsing the diagnosis of HGAP. We believe that integrated his- tologic and molecular analysis is essential to enable accurate diag- nosis of this rare brain tumour. E-PS-18 | E-Posters Ophthalmic Pathology E-PS-18-001 Pseudoglandular hyperplasia of the conjunctiva: report of a rare entity S. Graja*, S. Ben Tekaya, M. Rekik, O. Boudawara, M. Mellouli, A. Trigui, T. Boudawara, R. Kallel *Department of Pathology, Habib Bourguiba University Hospital, Sfax, Tunisia Background & objectives: Pseudoglandular hyperplasia of the con- junctiva (PHC) is a rare benign pseudo tumoral lesion which arises preferentially in conjunctiva fornix and/or tarsal. We report here a new case of this rare entity, review its histopathological features and discuss its differential diagnoses. Methods: The morphologic findings of PHC of the right eye occurring in a 65-year-old man were reported with a review of the related literature. Results: The patient consulted for a swollen pediculated conjunctiva mass. MRI revealed a well-limited hypervascular nodule, in the right upper palpebral conjunctiva, measuring 12 x 10 x 13 mm. Surgical excision was performed. On microscopic examination, the specimen received was covered with a regular stratified squamous epithelium containing numerous goblet cells. The epithelium realized invagination into the stroma with formation of pseudoglandular or pseudoadenomatous structures of various sizes. The surrounding stroma contained inflammatory cells with blood vessels. The lesion was focally ulcerated. There was neither nuclear atypia nor mitosis. The diagnosis of PHC was retained. Conclusion: PHC has distinctive histological features. It is defined as a proliferation of the conjunctival epithelium with prominent glandular structures. Clinical presentation and radiological features are not specific. Diagnosis is based on pathology analysis. PHC has good prognosis. Awareness of this entity is crucial to distinguish it from well-differentiated adenosquamous carcinoma to ensure the appropriate treatment. The absence of an infiltrative growth pattern and cytologic atypia with mitoses lead for PHC diagnosis. E-PS-18-002 Spindle cell haemangioma, an unusual presentation C.İ. Başsorgun, A. Yavuz*, M.Y. Çelik, Z. Bayramoglu, B. Unal, E.B. Türkoğlu Şen, G.O. Elpek *Akdeniz University Department of Pathology, Turkey Background & objectives: Spindle cell haemangioma (SCH) is a benign vascular tumour that occurs in the dermis or subcutaneous tissue of the hands and feet of young adults. SHC is occasionally associated with Maf- fucci syndrome, Ollier disease, and Klippel–Trenaunay syndrome. Methods: An 18-year-old male patient presented with a mass near the lacrimal gland in the left orbital region. Magnetic reso- nance imaging revealed a 7x13 mm nonspecific mass lesion in the left lacrimal gland localization with contrast enhancement. An excisional biopsy was performed from the masses in the left orbital region and sent to pathology. Results: Gross examination of the surgical specimen showed the 1.5x1.4x1 cm haemorrhagic lesion. Microscopic examination revealed two different components, thin-walled, large cavernous spaces and spindle epithelioid endothelial cells. There were 1-2 mitotic figures per 10 high-power field. Cellular atypia, atypical mitosis, necrosis, and pleomorphism were not observed. Immuno- histochemical examination revealed a positive reaction with CD31 and CD34 in cells lining the vascular spaces. Conclusion: The case was diagnosed as SCH. SCH is very unusual tumour in the orbital region. SCH should be considered as one of the differential diagnosis in vascular tumours of the orbit. Therefore, immunohistochemical examination should be performed to differenti- ate it from tumours such as orbital cavernous venous malformations, Kaposi’s sarcoma, angiosarcoma and epithelioid haemangioma. E-PS-19 | E-Posters Other Topics E-PS-19-001 Slide-free imaging of fresh bulk H&E-stained tissue using mul- tiphoton microscopy M. Strauch*, J.P. Kolb, C. Rose, N. Merg, J. Hundt, C. Kümpers, S. Perner, S. Karpf, R. Huber *Medical Laser Center Lübeck, Germany Background & objectives: Frozen sectioning is the gold standard for intraoperative histopathological examinations. We propose a laser-based microscopy technique to image bulk tissue directly in the operating theatre without having to freeze or section the tissue. Methods: We develop a laser-based multiphoton microscope intended for the special working conditions in the operating theatre. The feasibility of the microscopy system is evaluated using bulk porcine tissue samples which are stained with haematoxylin and eosin (H&E). The fresh bulk tissue is stained using a 6-7min H&E quick staining protocol and directly investigated under the microscope. Results: We obtain images of bulk unsectioned H&E-stained tissue within 15min. The laser microscopy technique evaluates the mor- phological structure at or slightly below the surface of the tissue. The H&E distributions in the tissue are recorded separately and can therefore also be evaluated individually. The images are inherently digital and can be analysed remotely by a pathologist and prevent delays due to sample transport to the pathology lab. S320