ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 to highly/moderately differentiated SqCC (p=0.020) and was decreased in N1 compared to N0 SqCC. In AdCa, DNMT3L_nu expression was higher in N0 compared to N1 carcinomas. No dif- ference in DNMTs expression was seen in correlation with the predominant pattern of AdCas (solid vs. acinar vs. lepidic vs. papillary). Conclusion: Increased nuclear expression of DNMTs in neo- plastic cells may account for DNA hypermethylation in various tumour suppressor genes seen in NSCLC. A heterogenous role for the different DNMTs is depicted in the different histologic types of NSCLC. Our results highlight a potential role for DNMT1 in SqCC and DNMT3L in AdCa. Further studies are needed to validate these results and analyse the functional role of DNMTs in the development and progression of NSCLC, in light of their potential therapeutic targeting. E-PS-21-009 Pulmonary metastasis of extraskeletal myxoid chondrosar- coma as a first sign of a disease A. Lovrenski*, N. Gardic, D. Tegeltija, I. Ergelašev *Faculty of Medicine, University of Novi Sad, Serbia Background & objectives: Extraskeletal myxoid chondrosarcoma (EMC) is an ultra-rare sarcoma subtype arised in the deep soft tissue. EMC demonstrate a strong tendency for local recurrence (37 - 48%) and metastatic disease (50%), usually pulmonary. Methods: A 59-year-old patient was hospitalized to clarify the aetiology of an 2,5 cm infiltrative lesion of the right lung discovered on on the thorax CT scan. The patient was operated when video-assisted thoracoscopy with atypical resection of the lower right lobe was performed. Results: Rapid on site evaluation imprint cytology, as well as fro- zen section pathohistological finding indicated a soft tissue tumour. FFPE section analysis revealed tumour tissue with multinodular architecture with increased tumour cellularity at the periphery of the lobules. Stroma consisted of abundant myxoid and chondromyxoid matrix into which tumour cells were immersed. Tumour cells were uniform, oval to round nuclei, eosinophilic and vacuolated cyto- plasm, organized into bands and small clusters. Nucleoli were small, but conspicuous. Occasional mitotic figures were identified. Foci of intralesional haemorrhages were frequently seen in various propor- tions. Immunohistochemical analysis showed tumour positivity for S-100 and neuron specific enolase (NSE) markers. Conclusion: Based on the histological findings and the results of immunohistochemical analysis, final diagnosis correspond to EMC, when the existence of a primary soft tissue tumour of other site was suspected. A detailed examination of the patient revealed a 4 cm tumour in the gluteal region that pathohistologically and immunohistochemically corresponded to EMC. Follow-up showed asymptomatic patient with no recurrence or new metastatic disease. E-PS-21-010 Epithelioid malignant mesothelioma with signet ring cells of the pleura - a case report C. Valavanis*, N. Novkovic, G. Stanc, N. Bolanos, M. Papazian, S. Stasinopoulou, E. Souka *Molecular Pathology Unit Metaxa Cancer Hospital, Greece Background & objectives: Malignant mesothelioma (MM) is an uncommon and very aggressive tumour arising from the mesothe- lial cells lining serous cavities. Signet ring cell epithelioid MM is an extremely rare subtype. Morphological subtypes of epithelioid meso- thelioma seem to have an impact on outcome. Methods: A 64-year-old male patient admitted to our hospital for chest pain. A CT scan was performed and a lesion of the right pleural membranes was found. The patient underwent a right thoracoscopy for pleural biopsies. Results: Multiple fragments of tumour tissue measuring 3X2X0,3cm were sent to the pathology department. The histo- pathologic examination revealed pleural infiltration by epithelioid cells with signet ring morphology and adenomatoid features in a solid and nested pattern. The neoplastic cells had eosinophilic cyto- plasm with cytoplasmic vacuoles, marked nuclear atypia, increased mitotic activity with 12mitoses /2mm2. No necrosis was observed. The immunohistochemical examination demonstrated the meso- thelial origin of the neoplastic cells, with positivity for WT1, cal- retinin, D2-40 and CK7. Negative immunoreactivity was observed for TTF1, CDX2, CK20, GATA-3 and PSAP. The diagnosis of high-grade diffuse epithelioid MM with signet- ring cell features, was made. Conclusion: Although epithelioid malignant mesothelioma is found in up to 80% of patients with MM, signet ring cell epithelioid MM is extremely rare, Architectural pattern, cytological features and nuclear grading have prognostic and diagnostic value. Median overall survival for this subtype is 15 months and the major diagnostic challenge is ruling out metastasis from other tumours featuring signet-ring cell morphology. E-PS-21-011 Foetal Adenocarcinoma of the lung - a case report C. Valavanis*, N. Novkovic, G. Stanc, M. Papazian, N. Baltagian- nis, M. Sevastiadou, E. Souka *Molecular Pathology Unit Metaxa Cancer Hospital, Greece Background & objectives: Foetal adenocarcinoma of the lung (FLAC) is a rare tumour, representing only 0.1%–0.5% of all pulmo- nary neoplasms. Approximately 25%–40% of patients are asymptomatic at presenta- tion, most of them with incidental findings. Methods: Male 54-years-old patient presented to our hospital for productive cough. On imaging a tumour was detected in the right lung, 2.5cm in diameter, as well multiple lesions in other regions of the right lung, up to 1cm in great diameter, without lymph node invasion. Right pneumonectomy was performed. One mediastinal lymph node and one subcarinal lymph node were also removed. Results: Histolopathological examination revealed a tumour featur- ing a high-grade conventional adenocarcinoma (positive for CK7, TTF-1, Napsin A, AFP, Glypican-3) with a >50% component show- ing morphology of an adenocarcinoma with clear cytoplasm, large vesicular nuclei, severe nuclear atypia, prominent nucleoli, supra- nuclear/ subnuclear vacuoles and frequent mitoses (positive only for CK7). Histochemical stains PAS and PAS-D showed glycogen production in the vacuoles. A diagnosis of high-grade foetal adenocarcinoma with negative lymph nodes was made. The neoplasm penetrated beyond the external elastic layer of the visceral pleura (PL1). One lesion from other pulmonary regions was an hamartoma with a small focus of foetal carcinoma, while the rest of them represented fibrous lesions with calcifications. Conclusion: Based on histopathological features and clinical course FLAC has been categorized into low-grade (L-FLAC) and high-grade (H-FLAC) subtypes. L-FLAC shows low nuclear atypia, S331