ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 R.A. Barna*, A. Jurescu, S. Taban, A. Muresan, A. Vaduva, V. Lupu, A. Dobrescu, B.R. Nataras, M.M. Bals, M. Cornianu *Department II Microscopic Morphology, Discipline of Morphopa- thology, ANAPATMOL Research Center, Victor Babes University of Medicine and Pharmacy, Timisoara, Romania Background & objectives: Anaplastic thyroid carcinoma (ATC) is the most aggressive form of thyroid cancer, arising from the thyroid follicular cells. It accounts for the majority of deaths from thyroid carcinoma. This study aimed to evaluate the clinico-pathological and immunohistochemical features of ATC. Methods: A retrospective-observational study was conducted over a 12-year period, between June 2009 and June 2021, including all patients diagnosed with ATC at the Emergency County Hospital from Timisoara. Medical records and histopathological features of tumour fragments, lobectomy and thyroidectomy specimens were analysed for all patients, as well as immunohistochemical markers (CK AE1/AE3, p53, Vimentin, Thyroglobulin, TTF-1, Ki-67) in some cases. Results: Twenty-one patients were diagnosed with ATC. The aver- age age at diagnosis was 70 years, and the female-to-male ratio was 9.5:1. On gross examination, the tumour was solid and par- tially encapsulated (57%), unencapsulated (19%) or not specified; the average maximal dimension was 5.5 cm. Histologically, all ATCs were hypercellular, with spindle or squamoid cells, marked nuclear pleomorphism, high mitotic activity and tumour necrosis. The growth pattern was infiltrative, with extrathyroidal exten- sion (62%), lymphovascular (71%) and perineural (43%) invasion. Twelve cases associated foci of differentiated thyroid carcinoma. Immunohistochemically, ATC expressed heterogenous positivity for CK AE1/AE3, p53, Vimentin; absent or weak expression for Thyroglobulin and TTF-1; mean Ki-67 index was greater than 60%. Conclusion: In our study, ATC affected older women more com- mon. Most cases were diagnosed in the advanced form, with aggressive morphological features and loss of thyroid differentia- tion, which makes the diagnosis more challenging for pathologists as well as for clinicians. Due to the frequent association of foci of well-differentiated papillary or follicular thyroid carcinoma, ATC could represent a gradually dedifferentiation of pre-existing well- differentiated thyroid carcinomas. Recognition of these features is crucial for the therapeutic management of patients with anaplastic thyroid carcinoma. E-PS-08-019 Lipoadenoma of the thyroid with bizarre nuclei and signet-ring cells: a case report A. Fitouri*, M.A. Bani, S. Cotteret, D. Hartl, L. Lamartina, V. Suciu, J. Scoazec, A. Al Ghuzlan *Pathology Department, Salah Azaiez Institute, Tunis, Tunisia/ Research Laboratory LR21SP01, Tunis, Tunisia Background & objectives: Variants of follicular adenomas include lipoadenoma, follicular adenoma with bizarre nuclei and signet-ring cell follicular adenoma. We report an exceptional case of lipoadenoma with bizarre nuclei and signet-ring cells and emphasize on pathologi- cal, immunohistochemical and molecular characteristics. Methods: A 78-year-old woman presented with a left thyroidal nodule measuring 31 x 20 mm. It was classified EUTIRADS 5 on ultrasonography. Fine needle aspiration showed sheets of tri- dimensional cells with hyperchromatic nuclei. Cytology was reported malignant Bethesda VI suggesting poorly differentiated carcinoma. The patient underwent total thyroidectomy and lymph node dissection. Results: Microscopically, the tumour presented micro-follicular and trabecular architecture with mixed adipose tissue. There were signet-ring cells associated to extracellular mucin. There were no vascular invasion and the tumour was well limited. Tumour cells had sparse marked anisokaryosis. Mitosis were rare (1/2mm²). Cells expressed TTF1, PAX8 and thyroglobulin. Adipose cells expressed PS100. Proliferative KI67 index was estimated to 1%. There were no expression of thyrocalcitonin, ACE, BRAF, Mam- maglobin, GCDFP15, GATA3, TRK and SOX10. RNA sequencing detected an oncogenic PPARG-PAX8 fusion. Definitive diagnosis was bizarre nuclei lipoadenoma associating signet-ring cell. Lymph nodes were negative. The last follow up was in March 2022 and the patient had no evidence of recurrent disease. Conclusion: This is the first case report of lipoadenoma with bizarre nuclei and signet-ring cells. The presence of bizarre nuclei and signet ring cells may lead to a misdiagnosis in cytology. The integrative pathology of morphology and immunohistochemical features led to the actual diagnosis. E-PS-08-020 A d r e n a l " P s e u d o - o n c o c y t i c ? " " R h a b d o i d ? " pheochromocytoma in a male suffering from Li-Fraumeni syndrome: What is it? A case report A.C. Loya*, A. Bondgaard, M. Klose, K. Wadt, K. Qvortrup *Rigshospitalet, Denmark Background & objectives: A rare variant of phaechromocytoma, ’oncocytic variant’, has been described only 6 times in literature. It has relatively high malignant potential. However, ’Pseudo-oncocytic/ Rhabdoid’ morphology/variant has never been described. Here we present case seen in pateint of Li-Fraumeni syndrome for discussion. Methods: Clinical examination, blood investigations, computed tomography (CT) scan, I-metaiodobenzylguanidine (123I-MIBG) scintigraphy and surgery were performed. Macroscopy, micros- copy (conventional hematoxylin and eosin staining and immuno- histochemistry) and transmission electron microscopy(TEM) were performed. The Pheochromocytoma of the Adrenal gland Scaled Score (PASS score) was used to evaluate the malignant potential of the tumour. Results: A 33-year-old patient, known with Li-Fraumeni syndrome had a right-sided adrenal mass found on CT in 2019. With a clinical diagnosis of pheochomocytoma, surgery was performed. Histology showed a pheochromocytoma, morphologically having oncocytic features but without increased number of mitochondria confirmed by Prohibitin immunohistochemistry and TEM, indicating a pseudo-oncocytic subtype. The cells could also be interpreted as ’rhabdoid’. Unfortunately, the final conclusion could not be taken about the variant, but more arrows are pointing to a pseudooncocytic type. Conclusion: So far in literature ’Pseudooncocytic/Rhabdoid’ sub- type has never, to our knowledge, been described. Presence of Li Fraumeni syndrome makes this more special, however the exact incidence and nature of this variant is unknown. For that matter, actual ’Oncocytic variant’ is also not clearly known because of paucity of cases. Therefore, further explorations are needed to label this variant and to contemplate its existence, if any. E-PS-08-021 What is the name of this tumour: malignant thyroid teratoma or thyroblastoma? S. Sevim*, E.K. Çagdas, T. Baglan, D. Enneli, S. Dizbay Sak *Ankara University Medical School, Pathology Department, Turkey S253