ECP 2023 Abstracts

S329 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 data was gathered including patient’s gender, age at disease onset, medical history, clinical findings, laboratory investigations, mode of diagnosis, therapeutic regime, recurrence rate and ocular and overall outcome. Results: A total of six patients had cytology confirmed PCNSL-O. All were diagnosed by pars plana vitrectomy. The average age was 72 years with a range from 58- 82 years old. Three patients were male and three were female. Four patients had bilateral ocular disease and two had unilateral. All patients were treated with chemotherapy and one had brain radiotherapy. MYD88 mutation was confirmed in three patients. IL-10: IL-6 ratio was >1 in the vitreous fluid of three cases which strongly assists the diagnosis of PCNSL -O. All patients are alive, four are disease free, one had CNS relapse and one is on first- line local chemotherapy treatment. Conclusion: This case series demonstrated excellent treatment out- comes with all six patients alive at the time of the study. Both local radiotherapy and chemotherapy achieved good ocular control. The high ratio of IL-10: IL-6 in the vitreous fluid strongly assists the diagnosis of PCNSL -O. MYD88 L265P mutation is a valuable diagnostic and promising tool; particularly in cases where limited vitreous material makes cytological evaluation challenging. However, molecular and interleukins results should be interpreted within the clinical and cyto- logical context. E-PS-18-003 Primary malignant melanomas of the uvea - a case report series E. Lampri*, I. Tragani, S. Sotiriou, P. Zafeiropoulos, D. Dimou, I. Parthymos, C. Kalogeropoulos *Department of Pathology, University Hospital of Ioannina, Greece Background & objectives: Uveal melanoma (UM) is the most fre- quent primary intraocular malignancy, however it represents a rela- tively rare neoplasm. A case series of UM of the past decade is derived from the archive of the Pathology Department of University Hospital of Ioannina. Methods: Nine cases of melanoma on specimens of orbital enu- cleation were included. Fixation, gross examination and sampling, in addition to Grading and Staging, were processed according to up-to-date version of the College of American Pathologists’ “Pro- tocol for the Examination of Specimens From Patients With Uveal Melanoma” on time of diagnosis. Microscopic evaluation involved standard hematoxylin-eosin staining and application of immunohis- tochemical markers. Results: Interestingly, seven out of nine patients were males with affection of the left eye (78%), while the mean age of diagnosis was 66 years (ranged 42-82). All tumours concerned choroidal melano- mas of medium to large size, with R0 excision, and two arised from pre-existing nevi. Six cases had mixed-cell histologic type and three cases had spindle-cell histologic type, whereas none qualified as an epithelioid-cell melanoma. Scleral involvement was found in five cases, one of which with extrascleral extension, and ciliary body was involved in three cases. Optic nerve invasion and vascular emboli were observed in only one case each (11% each). Pathologic Stage ranged between pT2a and pT3c. Conclusion: UM is a slow growing tumour with a high tendency to metastasize, particularly to the liver, even years after surgery. Metas- tases are associated with limited overall survival, hence detection and treatment of small lesions are essential for optimal patient care. Pathologists’ role in providing information about Grading and Staging is crucial, guiding treatment and follow-up surveillance. Our findings support prior literature regarding UM, except of high prevalence of left laterality, and hopefully will contribute to further understanding of this disease. E-PS-19 | E-Posters Paediatric and Perinatal Pathology E-PS-19-001 Ovarian central-type PNET of medulloepithelioma subtype in a young female S. Al-Dandan*, N. AlHawashim, M. Elhassan, H. Fatani *King Fahad Medical City/King Fahad Hospital Hofuf, Saudi Arabia Background & objectives: Primary primitive neuroectodermal tumour (PNET) of the ovary is a rare neoplasm. Medulloepithelioma is a sub- type of central PNET and a highly malignant embryonal tumour. There are only 13 cases described up to date in the English literature. Methods: A 16-year-old female patient presented with a right adnexal mass and ascites. The enhanced abdominopelvic CT scan revealed a large heterogeneously enhancing right ovarian mass associated with peritoneal and omental nodularity. The patient underwent right sal- pingo-oophorectomy and remained in remission for ten months until she developed peritoneal deposits. The patient eventually developed pancytopenia and pneumonia and died. Results: Histopathological examination of the salpingo-oophorectomy specimen revealed minor teratomatous growth with mature and imma- ture elements. The bulk of the tumour was composed of primitive neu- roectodermal tissue with variable morphologic patterns. There were anastomosing cords and loops of pseudostratified neuroepithelial cells in addition to papillary and tubular formations. The trabeculae focally encircled loose and pale vitreous-like mesenchymal tissue. Anaplastic features (nuclear gigantism and atypical mitoses) were evident. The apical surface was Alcian Blue-positive, while the basement membrane was PAS-positive. Tumour cells were reactive to PAX8 immunostain, indicating differentiation towards the ocular ciliary body. Next-gener- ation sequencing showed a pathogenic variant in the TP3 gene and no amplification of C19MC. Conclusion: Ovarian medulloepitheliomas are best viewed as mono- phasic teratomas due to their exclusive or almost exclusive neuroe- ctodermal composition. Despite aggressive therapy, the tumour dis- seminated and proved fatal within two years. The anaplasia and TP3 gene pathogenic variant may explain, in whole or part, the poor clini- cal outcome. The proper classification of medulloepithelioma remains unclear, and treatment protocols are yet to be established. E-PS-19-002 A fatal case of DiGeorge syndrome and tetralogy of fallot in a new- born: an autopsy report and histopathologic insights S. Andrei Dan*, M. Boro ș *Spitalul Clinic Judetean de Urgenta Oradea, Romania Background & objectives: DiGeorge syndrome, a congenital disorder resulting from a microdeletion at 22q11.2, is characterized by a hypo- plastic/absent thymus, cardiac malformations, including tetralogy of Fallot, and parathyroid hypoplasia. This case report aims to compare the antenatal diagnosis with autopsy and histopathologic findings. Methods: Antenatal diagnosis was made using genetic testing and imaging techniques, revealing thymus agenesis, corpus callosum agenesis and the tetralogy of Fallot. Postmortem examination was per- formed using standard techniques. Gross and microscopic examination was done on representative tissue samples. The autopsy findings were analysed and correlated with the antenatal diagnosis to evaluate the accuracy of prenatal diagnosis in DiGeorge syndrome. Results: The autopsy findings revealed craniofacial dysmorphism, hydrocephalus, as well as thymus hypoplasia, corpus callosum agenesis, hydronephrosis and hydroureter secondary to uretero-vesical stenosis, tight pulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy, confirming DiGeorge syndrome with tetralogy of Fallot and other anomalies. Following microscopic