ECP 2023 Abstracts

S287 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Methods: Histopathological examination of the mass was consistent with a Warthin tumour. Closer examination of the lymphoid stroma was significant for the presence of atypical hyperchromatic cells with ample clear cytoplasm arranged in sheets alongside the presence of numerous eosinophils and prominent proliferation of high endothelial venules with follicular dendritic cells. Results: The clear cells expressed T cell markers (CD3, CD5 and CD4) with the expression of T follicular helper markers: PD1, BCL6, CD10 and CXCL13. CD23 and CD21 positive clusters of follicular dendritic cells were noted in close proximity to the T cells and away from the B cell areas. In situ hybridization for EBV encoded RNAs was focally positive in scattered B cells whilst kappa and lamba were polyclonal. Conclusion: A diagnosis of Warthin tumour with involvement of the lymphoid stroma by a T-follicular helper (TFH) cell lymphoma, angioimmunoblastic-type was rendered. The pathologist should pay attention to both the lymphoid stroma and the epithelium when dealing with Warthin tumours as they can rarely be involved by lymphomas or carcinomas. E-PS-12-019 Lymphoepithelial cyst of the thyroid gland in the background of lymphocytic thyroiditis A. Faur*, D.C. Lazar, L.A. Ghenciu *”V. Babes” University of Medicine and Pharmacy, Romania Background & objectives: Lymphoepithelial cysts of the thyroid gland are relatively rare lesions of the head and neck region with only a few cases described in the current literature. We present a case report of branchial cleft-like lymphoepithelial cyst in a thyroid gland. Methods: A 41-year-old female presented to the Surgery Department of City Hospital Timisoara with a nodular goiter. A resection of the thyroid gland and regional lymph nodes was performed. Results: Macroscopically the thyroid was 5/5/1.5 cm with a cystic area in the right thyroid lobe of 2.5/1.2/1.1 cm. Microscopic examination revealed a cystic lesion with an epithelial lining represented by strati- fied squamous epithelium. Dense lymphoid tissue was present beneath the lining epithelium with lymphoid follicles and reactive germinal centres. In the rest of thyroid gland parenchyma there were present areas with extensive lymphocytic infiltrate with germinal centre for- mation and small follicles with oncocytes. The resected lymph nodes showed nonspecific findings with features like follicular hyperplasia and increased number of histiocytes. Conclusion: Lymphoepithelial cysts have been postulated to originate from the derivatives of the embryonic ultimobranchial body and were originally reported in 1989. Less than 40 cases were published and only a few were associated with Hashimoto thyroiditis. The differen- tial diagnosis in our case has to be made with Hurtle cells neoplasms, lithium intake, lymphoma thyroglossal duct cyst and Warthin-like thy- roid papillary carcinoma. E-PS-12-020 Hyalinizing trabecular tumour in a patient with oncocytic ade- noma, lymphocytic thyroiditis and papillary carcinoma of the thyroid gland A. Faur*, C.V. Gurban, L.A. Ghenciu, D.C. Lazar *”V. Babes” University of Medicine and Pharmacy, Romania Background & objectives: Hyalinizing trabecular tumour (HTT) comprises less than 1% of the thyroid neoplasms. We present the his- topathological and immunohistochemical findings in a case of HHT of a patient who also presented with multifocal papillary carcinoma, oncocytic adenoma and lymphocytic thyroiditis. Methods: A 65-year-old female presented to the Surgery Department of City Hospital Timisoara and a nodular goiter diagnosis was made by the clinician and a thyroidectomy was performed. Results: Macroscopically in the right lobe of thyroid gland two nodular areas with dimensions between 0.2-1.3 were described but also another two tan-coloured areas with diameters between 0.6-2 cm were identi- fied. The microscopic examination revealed that the two smaller areas had the features of a multifocal thyroid papillary carcinoma. From the two tan coloured areas one had aspects suggestive for an thyroid lesion of HHT and the other one of an oncocytic adenoma. An immu- nohistochemical analysis with MBME-1, CD56 and TTF-1 antibodies was performed. The final diagnosis was of multifocal papillary thyroid carcinoma with associated lesion of HHT, oncocytic adenoma in a background of lymphocytic thyroiditis (Hashimoto) and nodular goiter. Conclusion: Thyroid lesions are a heterogenous group of entities including rare and challenging tumours. E-PS-12-021 Medullary thyroid carcinoma, pigmented epithelioid melanocy- toma and pleomorphic adenoma with lymph-node metastases in the same patient - inherited cancer syndrome or coincidence? D.A. Grubišić*, T. Čeprnja, N. Kunac, K. Vilović *University Hospital of Split, Croatia Background & objectives: We present the patient with medullary thy- roid carcinoma, pigmented epithelioid melanocytoma and histologically benign pleomorphic adenoma with lymph-node metastases (MPA). Thy- roid cancer and melanoma can be part of Cowden syndrome. MPA is controversial entity with benign histology, but malignant behaviour. Methods: In 2014, after the surgery, the patient was diagnosed with medullary carcinoma of the right thyroid lobe and pleomorphic ade- noma of the right submandibular gland. No remaining tumour tissue was found in the extended surgery. In 2020, after the skin excision in the right infraorbital area, the patient was diagnosed with pigmented epithelioid melanocytoma. Results: USG examination in August 2021, showed, in the upper third of the right side of the neck, inhomogeneous hypoechoic nodule. Cyto- logical puncture raised the suspicion of metastasis of medullary thyroid cancer. In 2021, the neck discection of region I-V was performed. PHD diagnostic showed three lymph nodes in region II filled with tumour tissue composed of clusters of uniform myoepithelial cells with some epithelial cells or tubular structures lined with epithelial and myoepi- thelial cells surrounded by myxoid or chondromyxoid stroma, without polymorphism, necrosis and mitosis. Fewer smaller nodules in region I and II of the same histological composition were found. Described changes correspond to the recurrence of a pleomorphic adenoma. Conclusion: By searching the literature, these tumours cannot fit together into any hereditary form of tumour syndromes. Further research in terms of next generation sequencing or other genetic analy- sis would be preferred solution. Almost all tumour inherited syndromes are rare and cause variety of symptoms. It is important to make patients and doctors aware of the existence of these conditions in order to detect a greater number of such patients through timely diagnosis and thus prevent the further development of cancers. E-PS-12-022 Evaluation of miR- 21 and PDCD4 expression in liquid biopsies of oral dysplasia and oral squamous cell carcinoma patients S.E. Gultekin*, L. Bozdag, L. Acik, N. Mollaoglu, E. Ersoy, O. Bayir, M.H. Korkmaz *Gazi University Faculty of Dentistry, Turkey Background & objectives: Liquid biopsy plays a pivotal role in non- invasive detection of cancer at the early stages of the disease. We aimed to determine miR -21 and PDCD4 expression levels in saliva and blood samples of oral dysplasia and oral cancer patients. Methods: The study was carried out in blood and saliva samples, obtained from oral dysplasia (OD) (n:15) oral squamous cell carcinoma