ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 has an indolent course. This study aims to describe its epidemiological, histologic characteristics and to provide data on outcome after surgery. Methods: We retrospectively analysed 31 consecutive patients with PTMC who underwent surgery at our institution between 2012 and 2021; 27 of them (87% of cases) were treated also with radioiodine therapy and followed for at least 1 year. The data on patients gen- der, age, morphological characteristics, extent of disease, therapy, locoregional and distant control were collected. Results: There were 26 women and 5 men. The mean age was 53.5. Most of the PTMCs were diagnosed incidentally during pathologic examination. Median tumour size was 5.5 mm. 16% of PTMCs showed multifocality, with 3 cases of unilateral multifocal lesions and 2 cases with bilateral multifocal tumours. TNM stages were I in 30 patients (96.77%) and III in one patient (3.2%). A total of 18 cases (58%) had regional lymph node sampling and 3 of them were metastatic (9%). 25 patients (80.64%) underwent bilateral lobar resection. During the follow-up period, the recurrence was diag- nosed in only 1 patient (locoregional recurrence one year later). There were no PTMC related deaths. Conclusion: The prognosis for patients with papillary thyroid microcarcinoma in this serie was excellent, with a 100% survival rate and and a low rate of recurrence associated with PTMC. Nevertheless, approximately 3% of patients developed recurrent disease; aggressive treatment may be justified depending on the presence or absence of prognostic risk factors. E-PS-08-025 Reliability of frozen section thyroid examination: through a series of 536 cases F. Sassi*, L. Bel Hadj Kacem, A. Blel, R. Aloui, A. Bani, N. Ben Othman, M. Ksentini, N. Znaidi, S. Rammeh *Department of Pathology, Charles Nicolle Hospital Tunis, Tunisia Background & objectives: Frozen section examination (FSE) of thy- roid nodules is an essential step in guiding surgical procedures and aiming for optimal patient management. The purpose of this study was to evaluate the reliability of FS according to definite histologic examination. Methods: This was a retrospective study conducted on 536 thyroid resection specimens sent for FSE over a 4-year period. FSE’s results were compared to the final microscopic examination (FME),. The diagnostic value of FSE was evaluated by calculating sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV). Delayed results were excluded from statistical analysis. Results: The population included 452 women and 84 men (aver- age age: 49.9 years). The 536 FS were benign in 284 cases (53%), malignant in 60 cases (11.2%) and the response was delayed in 192 cases (35.8%). The FME showed that among the 284 nod- ules considered benign, 224 were truly benign and 60 were malig- nant. Among the 60 malignant, 56 were carcinomas: papillary (52), vesicular(3) and undifferentiated(1) and 4 were benign. The delayed results were benign in 76 cases, malignant in 112 cases and lesions of uncertain malignancy in 4 cases. The Sp was 98.3% with a PPV of 93.3% and the Se was 48.3% with a NPV of 78.9%. Conclusion: FSE is very reliable with a Sp approaching 100%. The rate of thyroid carcinomas reported varies from 4.5 to 26.3%, depending on the series. In our study, it was 11.2%. Most of series showed false positivity (FP) between 0.1 to 0.6% and Sp between 50 to 92% which is comparable to our series, where we found FP in 0.7% and Sp in 98.3%. The low Se was related to encapsulated vesicular lesions, technical problems, nuclear artifacts and difficulty of microcarcinoma’s identification. E-PS-09 | E-Posters Gynaecological Pathology E-PS-09-001 Squamous cell carcinoma of the ovary associated with endome- triosis: a case report I. Bernal Simón*, M. Rezola Bajineta *Donostia University Hospital, Spain Background & objectives: To analyse the clinical, therapeutic and pathologic features of a primary squamous cell ovary carcinoma case associated with endometriosis. This is a rare entity that accounts less than 1% of primary ovarian malignant tumours. Methods: 52 years old woman presented to gynecological consult for abnormal vaginal bleeding and lower abdominal pain. She had no history of malignancies or relevant diseases. Physical examina- tion and imaging showed several uterine nodules consistent with myomas and a torsion of the right ovary with central necrosis. The patient underwent surgery, performing total hysterectomy with left salpinguectomy and right adnexectomy. Results: On microscopic examination, moderately differentiated squamous cell carcinoma of the ovary was seen displaying a diffusely infiltrative pattern with abundant keratinization and extensive necrosis. The cells had pleomorphic nuclei with conspicuous nucleoli and ill defined citoplasmic borders. Central areas showed abundant keratin formation with some calcifications. Isolated glandular formations without atypia were observed in the ovarian cortex consistent with endometriosis. The ovary was entirely submitted and did not reveal other lesions like teratoma or Brenner tumour. Surgical staging was performed showing a peritoneal implant. The patient received paclitaxel, carboplatin and bevacizumab. At the moment, she is disease-free after 14 months of follow-up. Conclusion: Squamous cell carcinoma of the ovary is an infrequent tumour with few cases reported in the literature. It has poor prognosis and in most cases arises from mature cystic teratoma with malignant transformation or less frequently shows association with endometriosis or Brenner tumour. The pure form is not related with any of the conditions mentioned before. Optimal debulking surgery and adjuvant chemotherapy seem to be the best treatment option in advanced disease but further studies are needed. E-PS-09-002 Malignant transformation of ovarian mature teratoma: a 20-year experience of Tunisian centre A. Bchir, N. Abdessayed*, T. Tlili, S. Mabrouk, M. Mokni *Department of Pathology, Farhat Hached University Hospital, Sousse, Tunisia Background & objectives: Mature teratoma is the most common tumour of ovary. It is usually a benign germ cell tumours. Malignant transformation is extremely rare. The objective of our study is to high- light the clinico-pathologic characteristic of malignant transformation of ovarian mature teratoma. Methods: A total of 6 cases of mature teratoma with malignant transformation at the Department of Pathology and Gynaecology of Farhat Hached University Hospital in Sousse, over a period of 20 years (from 2000 to 2019). A review of clinical, paraclinical, pathological and evolutionary data was performed in all cases. Results: The prevalence of mature teratoma with malignant trans- formation was 0.12%. The average age was 57.5 years. The main clinical presentation was abdominal pain. The main tumour size was 15.1 cm. 3 tumours were in the right, one case were in the left and 2 were bilateral. Abdominal sonography was an essential exam for the diagnosis. There were 3 squamous carcinoma, one melanoma, one intestinal type adenocarcinoma and one vesicular S255