ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: Poorly differentiated thyroid carcinoma (PDTC) is a rare tumour type originating in the thyroid follicular cells. The presence of pleomorphic tumour giant cells in PDTC is always worrisome for the pathologist as they usually refer to anaplastic carcinoma. Methods: We report the case of a 31-year-old female admitted to the hospital for a right thyroid macronodule, suspicion for follicular neoplasm in cytology. Total thyroidectomy was performed and the specimen was sent to the Pathology Department. Results: On macroscopy, the left right lobe was almost entirely replaced by a whitish nodule of 54 mm. On microscopy, the nodule was surrounded by an irregular capsule, with suspicion of vascular invasion. The nodule was solid with large tumour nests/islands, separated by thin, fibrous septa. Small foci of endocrine-type necrosis were also present. The tumour was composed of monoto- nous tumour cells, with round-ovalar centrally placed nuclei, with prominent nucleoli. But focally pleomorphic giant cells with an abundant eosinophilic cytoplasm and large, irregular, sometimes frankly monstrous nuclei were seen. The mitotic index was 6 mitosis/10HPF. On immunohistochemistry the tumour cells and the pleomorphic giant cells expressed both thyroglobulin and TTF-1. Conclusion: The immunohistochemical profile of the pleomorphic giant cells indicates not only their follicular origin but above all their differentiated nature. This case shows that pleomorphic tumour giant cells arising in PDTC do not always represent dedifferentiation and progression to anaplastic carcinoma. Distinction among these processes is critical as their treatment and prognosis are very different. E-PS-08-012 Gamna-Gandy bodies: a rare finding in a papillary thyroid carcinoma J. Almeida*, A. Costa Braga *Department of Anatomic Pathology, Centro Hospitalar Universi- tário de São João, Portugal Background & objectives: Gamna-Gandy bodies (GGB) are fibrous tissue coated by iron and calcium with unusual articulated and bamboo- like fibres. GGB are currently thought to be caused by minor haemor- rhages, mostly in spleen and atrial myxomas, rarely reported in other locations. Methods: A 46-year-old woman displaying multinodular goiter and primary hyperparathyroidism, underwent total thyroidectomy and parathyroidectomy. Gross and histological examination were performed, including additional histochemical techniques – Perls and Von Kossa (VK) stains. Results: We report a case of a multifocal Papillary Thyroid Carci- noma (PTC), measuring 32mm in its largest dimension, in a back- ground of a nodular hyperplasia. Sclerotic areas with mycelia-like appearance were found within the PTC. Perls and VK highlighted the iron and calcium encrusted fibres, compatible with GGB. So far, only rare cases of thyroid GGB have been reported, all of them associated with follicular adenomas and nodular hyperplasia, none associated with PTC. It is unknown if the coexistence of nodular hyperplasia has contributed to GGB formation in this case. The patient underwent radioiodine ablation and is alive with no evi- dence of disease 17 months after the surgery. Conclusion: Knowing that the thyroid is a richly vascularized organ and that the haemorrhage process is the origin of GGB formation, it would be expected more cases of thyroidal GGB. Perhaps a low interest in GGB justifies the scarcity of this entity. With this case we intend to underline the importance of reporting GGB and carry out the review of cases of neoplasms associated with GGB, especially in thyroid, in an attempt to clarify their meaning and potential impact. E-PS-08-013 Papillary thyroid microcarcinoma - tall cell variant arising in mature cystic teratoma of the ovary - a case report S. Al Bashir*, M. Alorjani, I. Matalka, M. Alfaqih, N. Obeidat *King Abdullah University Hospital, Jordan University of Science and Technology, Jordan Background & objectives: Presence of malignancies in somatic parts of mature cystic teratoma (MCT) of the ovary is rare. We present a case of tall cell variant (TCV) of papillary thyroid microcarcinoma (PMC) arising in MCT of the ovary. Methods: A 31-year-old female patient presented with a left ovar- ian cyst which on ultrasound scan showed measured 5.0 × 5.0 cm and was likely MCT. Laparotomy with cystectomy was performed. Grossly, it was an intact unilocular cyst with smooth surface, filled with tufts of hair and sebum (0.1 cm thick) with only small thick- ened area (1.0 x 0.8 x 0.6 cm). Results: Microscopically, the cyst wall was lined by stratified squamous epithelium and contained mature tissues (skin, appendages, respiratory epithelium, cartilage and thyroid tissue). In the thickened area, there was a small focus of thyroid tissue; within which PMC (0.6 cm) was noted, composed of trabeculae and follicles of tall cells. Diagnosis: PMC-TCV, arising from a small focus of thyroid tissue in MCT with maximum tumour size of 0.6 cm. The patient under- went US scan of the thyroid gland and computed tomography scan of the neck and chest with no clinical evidence of tumour metasta- sis. The patient has been on follow-up with for 4 years post-surgery with uneventful recurrence-free clinical course. Conclusion: Our case is a PMC diagnosed in a small focus of thy- roid tissue within MCT (not meeting diagnostic criteria for struma ovarii), different from two previously reported cases of PTC in struma ovarii. To our knowledge, this is the first case of PMC-TCV arising in MCT with conservative surgery. Such treatment modality may be an alternative to previously suggested more radical options. However, standardization of treatment protocols requires immedi- ate reporting of secondary malignancies in MCTs and referral to large databases. E-PS-08-014 Core-needle biopsy in the diagnosis of thyroid lesions - risky or diagnostically helpful? E. Bakuła-Zalewska*, J. Długosinska, P. Góralski, J. Gałczynski, M. Durzyńska, M. Chraszczewska, A. Stanek-Widera, M. Prochorec-Sobieszek *Department of Pathology, Maria Sklodowska-Curie National Research Institute of Oncology; MSCNRIO, Poland Background & objectives: Diagnosis of thyroid tumours is routinely based on an ultrasound guided fine needle aspiration biopsy (FNAB). In some cases, however, FNAB fails and CNB may be an alternative diagnostic tool. Methods: The study was conducted over a period of 4 years, 2019- 2022. Twenty-seven patients with thyroid tumours larger than 2cm, suspicion of malignancy and insufficient repeated FNAB, under- went CNBs of the thyroid at NIO-PIB in Warsaw. Results: Diagnostic material was obtained in 24 patients, in remaining 3 cases CNB was performed twice to obtain material sufficient for microscopic examination, immunohistochemical and molecular tests (NGS). For one patient with suspicious Hodgkin lymphoma the final diagnosis required a surgical biopsy of the lymph node. There were 5 anaplastic carcinomas, 2 poorly differ- entiated carcinomas, 1 medullary carcinoma, 1 PTC, 5 metastatic carcinomas (2 SCC, RCC, HCC, mucoepidermoid carcinoma) 3 S251