ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 L. Lozneanu*, C. Andriescu, I.D. Caruntu, S.E. Giusca, R. Danila, A. Grigorovici, C. Preda, D.G. Ciobanu Apostol *"Grigore T. Popa" University of Medicine and Pharmacy Iasi, Romania Background & objectives: Thyroid carcinomas are the most common endocrine tumours malignancies. Follicular thyroid carcinoma (FTC) and Hurthle (oncocytic) cell carcinoma (HCC) accounts for 15% of cases. The aim of this study was to identify the differences between the two entities. Methods: The retrospective study comprised 56 consecutive cases of FTC (40 cases) and HCC (16 cases) was investigated during 2007-2020. All cases were reviewed by three independent patholo- gists in order to establish the histological variant and to reassess the main characteristics. Statistical correlations between FTC and HCC and various clinicopathological parameters were also performed. Results: FTC presented: age (mean 52); female 75%; size 8-93 mm; minimally invasive (33 cases), widely invasive (5 cases), encapsulated angioinvasive (2 cases); collision tumour (8 cases); capsule invasion (13 cases); extrathyroidal extension (4 cases); lymph node metastasis (2 cases), lymphovascular invasion (30 cases), relapse (1 case); tumour stage T2-T4 (34 cases). HCC presented: age (mean 57); female 87.50%; size 21-80 mm; collision tumour (3 cases); capsule invasion (2 cases); extrathyroidal extension (1 case); lymph node metastasis (2 cases); lymphovascular invasion (15 cases); tumour stage T2-T4 (13 cases). All cases presented unilateral involvement and associated thyroid pathology. Significant differences were noted between FTC and HCC only with lymphovascular invasion (p= 0.038). Conclusion: In thyroid carcinoma with follicular architecture, FTC versus HCC, parameter of aggression determined only by lymph- vascular invasion, date obtained with statistically significant dif- ferences (p=0.038), in relation to the other classical clinicopatho- logical features. As evidenced by the cases we present, HCC are tumours with aggressive clinical behaviour and high metastasis potential, compering to FTC. E-PS-08-009 Poorly differentiated thyroid carcinoma, an unusual tumour in young patients. Report of two cases A. Borda*, E. Szasz, D. Burlacu, A. Loghin, A. Nechifor- Boila *Histology Department, UMFST G.E. Palade Tg. Mure ș , Romania Background & objectives: Poorly differentiated thyroid cancer (PDTC) is a rare aggressive thyroid malignancy with a unique feature in morphology and behaviour. In young individuals it is a very unusual observation and its clinical feature, genetic mechanism and outcome is poorly understood. Methods: In this study we report two cases of PDTC in a 31- and 34-year-old patients. Both patients were admitted to the surgical department of Mures County Emergency Hospital with a Bethesda 5, suspicious for malignancy thyroid cytology. A total thyroid- ectomy was performed and the specimens were analysed in the Pathology Department. Results: On microscopic examination both tumours were encapsulated and had an insular, trabecular and/or solid tumour growth. One of the tumours, of 54 mm, had angioinvasion. Both cases met the Turin criteria for PDTC diagnosis: tumour cells were small, monotonous, with few cytoplasm and convoluted nuclei. Both tumours displayed necrosis and more than 5 mitoses per 10 HPF. No features of differentiated thyroid carcinoma were noticed. In one of the tumour, intermingled with the monotonous cells, pleomorphic giant tumour cells with bizarre features were noticed. In immunohistochemistry these cells expressed Cytokeratin, Thyroglobulin, TTF-1 and PAX 8, proving their follicular origin, and also their non- anaplastic character. Conclusion: We should always keep in mind that PDTC may occur in young individuals. Its association with pleomorphic tumour giant cells do not always represent tumour dedifferentiation. As PDTC accounts for most fatalities from non-anaplastic thyroid cancers, a correct diagnosis is important for clinicians and oncologists to predict the prognosis. E-PS-08-010 Pituitary neuroendocrine tumours and non-neoplastic adeno- hypophysis arising in ovarian teratomas: a likely under-recog- nised phenomenon A. Hodgson*, S. Ahmad Thiryayi, O. Mete *Toronto General Hospital, Canada Background & objectives: Recently, our group has identified and comprehensively characterized both non-neoplastic adenohypophysis and pituitary neuroendocrine tumours (PitNETs) occurring in ovarian teratomas. Our objective is to highlight the role of histochemical and immunohistochemical tools in recognizing and properly classifying these proliferations. Methods: PitNETs and non-neoplastic adenohypophysis arising in ovarian teratomas were identified from our institutional records. Adenohypophyseal tissues were assessed using reticulin histochem- istry and immunohistochemical biomarkers (pituitary transcription factors including PIT1, TPIT, SF1, ER-alpha, GATA3, adenohypo- physeal hormones, alpha-subunit, CAM5.2, S100 and MIB1). All included cases were reviewed by both endocrine and gynecologic pathologists. Demographic and clinicopathologic information was recorded for each case. Results: One of five teratomas was immature. Three PitNETs and two non-tumorous adenohypophyseal proliferations were identified (median patient age 26 years; range 16-67). The PitNETs were all of PIT1-lineage: 2 sparsely granulated lactotroph tumours (0.15 and 0.4 cm) and 1 mixed sparsely granulated lactotroph and densely granulated somatotroph tumour (0.15 cm). The MIB1 labelling index (LI) ranged from < 1% to 1.5%. Unlike the PitNETs, the two cases of non-tumourous adenohypophysis were composed of admixed PIT1, TPIT and SF1-lineage cells with a MIB1 LI < 1%, demonstrated interspersed S100-positive folliculostellate cells and showed no reticulin disruption. Conclusion: Both non-neoplastic adenohypophysis and PitNETs occur in ovarian teratomas and may be mistaken for other neu- roendocrine neoplasms. Reticulin histochemistry and immunohis- tochemical biomarkers are required to confirm adenohypophyseal cell origin, distinguish nontumourous elements from PitNETs, and subtype and prognosticate PitNETs, if applicable. Further epide- miological studies are needed to determine the prevalence of Pit- NETs and non-tumourous adenohypophysis in ovarian teratomas. E-PS-08-011 Poorly differentiated thyroid carcinoma associated with pleomorphic tumour giant cells: report of a challenging case E.A. Szasz*, A. Nechifor- Boila, D. Burlacu, R. Catana, M. Vlad, A. Borda *George Emil Palade University of Medecine, Pharmacy, Science, and Technology of Targu Mures, Romania S250