ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 E-PS-11-035 Thyrolipoma, a case report with literature review Z. Lajmi*, T. Tlili, S. Mabrouk, Y. Fejji, B. Sriha, M. Mokni *Department of Pathology, Farhat Hached University Hospital, Tunisia Background & objectives: Thyrolipoma (TL) also called adenolipoma of the thyroid gland is distinctively rare. Less than 50 cases have been reported in the English literature so far. We describe a representative case of TL along with a brief literature review. Methods: A 57-year-old woman, with no relevant medical his- tory, presented with a painless neck lump which have been slowly increasing in size for 2 years. Physical examination and ultra- sound imaging showed a well defined, 4 cm, predominantly cystic, TIRADS 3 nodule in the left lobe of the thyroid gland. A left hemithyroidectomy was performed. Results: Surgical specimen weighted 28 g. The left lobe of the thyroid measured 4,5 x 4 x 4 cm. Cut section showed a 3.7 cm, medio-lobar, well-circumscribed, mainly cystic nodule, with haemorrhage and a few brittle yellow foci. Two smaller, well defined, solid nodules measuring 4 and 7 mm were also identified. On microscopic examination, all 3 nodules were surrounded by fibrous capsules and consisted of mature adipocytes admixed with bland-looking thyroid follicles. The adipose lobules accounted for at least 40% of the total nodules sections. The remainder of the thyroid tissue was unremarkable. Conclusion: Most reported cases of TL occurred in women, var- ied in size from 0.3 to 25 cm and presented as a solitary lesion or in association with multinodular thyroid hyperplasia, papillary carcinoma or thyroiditis. TL should be distinguished from thy- rolipomatosis characterized by fat diffusely distributed throughout the thyroid gland. The two conditions can rarely coexist. Some thyrolipomas present as extrathyroidal nodules and should not be mistaken with enlarged parathyroid glands which normally contain adipose tissue and may display a follicular pattern. E-PS-11-036 Mesenchymal chondrosarcoma of maxillary bones: two case reports A. Fitouri*, P. Khneisser, M. Classe, C. Ngo, S. Cotteret, O. Casiraghi *Pathology Department, Salah Azaiez Institute, Tunis, Tunisia; Research Laboratory LR21SP01, Tunis, Tunisia Background & objectives: Mesenchymal chondrosarcoma (MCS) is a very rare and aggressive malignant bone tumour occuring in femur, pelvis, ribs and facial bones, with 25% of cases in the jaws. Methods: We report two cases of maxillary MCS in a 65 and a 26 years-old women respectively, who presented a large submucousal tumour of the hard palate. In the first case, TDM and MRI were in favour of a chondrosarcoma. Results: On biopsies, the first case presented a proliferation made of large atypical cells lying in a chondroid matrix, surrounded by small foci of small round blue cells showing « crush artefacts ». The second case presented atypical and mitotic small blue cell nests densely packed around vessels and separated by chondromyxoid trabeculae. The chondroid component showed a nuclear positivity for PS100+ and were SATB2-, MDM2-, CD99- and NKX2.2-; and conversally, the« mesenchymatous » component, a membranous positivity for CD99+, a nuclear positivity for NKX2.2+ and were PS100-. The presence of a HEY1-NCOA2 gene fusion confirmed the diagnosis of MCS. Surgery was performed, followed by radio- therapy in the first case. Conclusion: MCS is a biphasic tumour, with an undifferentiated small blue cell component and a well-differentiated cartilaginous component, and a highly specific HEY1-NCOA2 gene fusion. When facing a chondroid tumours of the jaws, both chondrosar- coma and chondroblastic osteosarcoma hypotheses must be raised, but small blue cell foci that could suggest a MCS must be searched for. Conversally, it is important in malignant blue cell tumours, to look for foci of cartilaginous differentiation. A molecular confir- mation is necessary in this tricky diagnosis. E-PS-11-037 Solitary neurofibroma of maxillary sinus expanding to nasal cavity and orbit J.P. Skliris*, S. Papadopoulou, K. Marini, N. Pastelli, I. Dimitri- adis, I. Matzarakis, S. Papaemmanouil *Papanikolaou General Hospital of Thessaloniki, Greece Background & objectives: Neurofibromas are benign peripheral nerve sheath tumours with infiltrative potential. We present a case of a large and unusually located sporadic neurofibroma that occupied a great extent of craniofacial regions. Methods: Otolaryngologists of our institution, following clinical examination and imaging, located and were able to biopsy a large tumour protruding from the left maxillary sinus of a 59-year old female patient. This mass seemed to be extending inside the left nasal cavity and possibly reaching the adjacent orbit with radio- logical signs of osseous erosion. Results: Histopathology report described a neoplastic lesion consisting of sparse, uniform cells with wavy nuclei inside a collagenous stroma. Only rare mitoses and no necrosis or atypia were observed. Mitotic index using Ki-67 was calculated about 1%. During ancillary examinations, the neoplastic population stained for S100, CD34 (focally) and EMA (focally), whereas was negative for CD117, Ck8/18 and MelanA. The diagnosis of neurofibroma was concluded. Conclusion: In conclusion, the case described aims to increase awareness among clinicians and diagnosticians of this very rare site of this already quite uncommon entity, with only a few cases described in the existing literature. E-PS-11-038 A forgotten entity in parotid gland lesions differential diag- nosis – a case report S. Antunes*, C. Dahlstedt Ferreira, R. Oliveira, M. Lopes Oliveira, D. Gomes Pinto *Hospital Garcia de Orta, Portugal Background & objectives: Haemangiomas are benign vascular abnor- malities characterized by an increased proliferation and turnover of endothelial cells, accounting for 0.4-0.6% of all parotid gland tumours. They are common in infancy but extremely rare in adults, often misdi- agnosed before surgical resection. Methods: A 85-year-old woman presented in 2018 with a parotid nodule with 3x2,5cm. Between 2018 and 2021 she underwent 4 fine- needle aspirations (FNA), all constituted by blood and few epithelial cells, all considered non-diagnostic. Computed Tomography scan and Magnetic Resonance Imaging were inconclusive, favouring a benign tumour, and suggesting the possibility of a vascular lesion. Results: In January 2022 a tumourectomy was performed. Intraop- eratively, a vascular lesion involving the deep lobe of parotid gland was identified. Grossly, the specimen measured 5,5x5x2 cm and weighted 216,5 g. The cut surface revealed a multinodular expansive brown lesion, with white areas. It measured 3,3x3,2x1,4 cm and was partially coincidental with the excision margin. Microscopically, a S289