ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 wide resection may not be possible due to proximity to vital structures. High index of suspicion and an adequate clearance is the key to successful treatment. E-PS-11-007 Primary small cell neuroendocrine carcinoma of the tonsil: a case report G. Galanopoulos*, E. Souka, S. Laskaris, M. Terzi, L. Karelis, O. Tzaida *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Neuroendocrine tumours account for 0.5% of all malignancies and are mainly found in the gastrointestinal track and the lung. We present a very rare case of primary small cell neu- roendocrine carcinoma (NEC) of the right tonsil. Methods: A 82-year-old male patient was admitted with symptoms of throat pain and dysphagia. Clinical examination revealed a right tonsil mass along with a palpable right inguinal lymph node. A biopsy of the tonsillar mass, as well as a fine needle biopsy (FNB) of the lymph node was performed. Results: Microscopical examination of the tonsillar mass showed small round to oval tumour cells arranged in nests or rosettes with granular nuclei and scant cytoplasm. Apoptosis, necrosis and numerous mitotic figures (>10mit/2mm2) were also found. Immu- nohistochemical staining was positive for CKAE1-AE3, CK8-18, CK20 (dot-like pattern), chromogranin and synaptophysin. Ki-67 mitotic index was high (>80%). Same histopathological results were identified on the lymph node FNB. The aforementioned fea- tures of the tumour established the diagnosis of a primary poor- differentiated small cell neuroendocrine carcinoma of the tonsil with inguinal lymph node metastasis. Conclusion: Small cell NEC that primarily occurs in tonsil is extremely rare with an aggressive disease course and poor prog- nosis (18 months median overall survival time). During the past 40 years, there have been only 14 cases added in the English literature with a male predominance. Paraganglioma and malig- nant lymphoma should be considered in the differential diag- nosis. Owing to its rarity, standard treatment protocol remains uncertain. E-PS-11-008 A case of multiple cutaneous squamous cell carcinomas of the head and neck in a patient with primary lung adenocarcinoma Y. Topalov*, A. Vlahova, E. Aleksiev, M. Genadieva *Alexandrovska University Hospital, Bulgaria Background & objectives: Here we present a case of multiple skin nodules in the head and neck area arising simultaneously in a 70-year- old man just diagnosed with primary lung adenocarcinoma. The clinical suspicion was skin metastases. Methods: During chemotherapy and immunotherapy for the lung tumour the nodules shrunk in size. The clinical suspicion was skin metastases. Incision biopsy was performed on some of the nodules and they were histologically and immunohistochemically examined. Results: Histology revealed poorly differentiated epithelial tumours and immunohistochemical studies confirmed them to be of squamous origin. A diagnosis of eruptive primary cutaneous squamous cell carcinomas was made. Conclusion: Although rare, the possibility for multiple simulta- neous primary malignancies should always be in the differential diagnosis with metastatic disease, and clinical response to therapy cannot be used as a reliable distinguishing criterion. E-PS-11-009 NTRK-rearranged thyroid carcinomas with evidence of ana- plastic transformation in lymph node metastases: clinicopatho- logical and molecular features I. Laklouk* *University of Wisconsin-Madison, USA Background & objectives: The actionable NTRK-rearranged thyroid carcinoma carcinomas (PTC) are not infrequently clinically aggres- sive and are predominantly differentiated follicular-derived carcino- mas. Rare NTRK-rearranged PTCs have shown disease progression and aggressive clinical behaviour, but their pathologic and molecular features remain understudied. Methods: Of 40 BRAF negative PTCs available for review, we identified 3 NTRK-rearranged thyroid carcinomas. We examined the clinicopathological and molecular features of 3 NTRK-rear- ranged thyroid carcinoma cases. Results: One NTRK-rearranged PTC, despite surgical, radioio- dine/chemotherapy, had multiple lymph nodes/local recurrences over 17 years. The most recent recurrence demonstrates biphasic components of differentiated PTC and dedifferentiated (anaplastic transformation) anaplastic transformation with sarcoma-like mor- phology. Immunostains show that AE1/3 and PAX8 are positive in differentiated-PTC but negative in the dedifferentiated component. Both components are negative for TTF-1, desmin, and p53. Ki-67 is 40% in dedifferentiated carcinoma and less than 10% in the dif- ferentiated PTC. NGS showed ETV6-NTRK3 gene fusion, BCL3, and BCL9 in both components. The other two NTRK-rearranged cases show indolent clinical behaviour with neither high-grade fea- tures nor anaplastic transformation in their primary tumours or in lymph node disease Conclusion: This report identified a recurrent PTC with ETV6- NTRK3 gene fusion mutation that was prone to undergo an anaplastic transformation with sarcoma-like morphology in the nodal recurrence, which may mimic other spindle cell sarcomas. This finding, also, has important implications for clinical outcomes and aggressive clinical behaviour E-PS-11-010 Malignant melanoma metastasis in a parotid lymph node, with- out an identifiable primary site L. Banias*, R. Chiciudean, I. Jung, D. Szava, Z. Kovacs, S. Gurzu *George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Romania Background & objectives: The parotid gland hosts metastases, but most often from primary tumours of the head and neck region, which have the potential of spreading to the regional lymph nodes, such as cutaneous squamous cell carcinomas or cutaneous melanomas. Methods: A 58-year-old male patient was admitted to the Oral and Maxillofacial Surgery Department with a tumour nodule that has been located in the right preauricular area for two years and which grew rapidly two months before presentation, for which a right partial parotidectomy was performed and the nodular mass was sent for histopathological examination. Results: The macroscopic aspect showed a 35x35x10 mm encap- sulated nodule, with tan and white colour areas on the cut section. Histopathological evaluation revealed lymphoid tissue pushed to the periphery and mostly replaced by a proliferation of atypical, pleomorphic cells, with melanin pigment content, arranged in clus- ters and placards, with areas of haemorrhage and necrosis. The neo- plastic cells presented BRAF-V600E/EC gene mutation, expressed HMB45, MelanA, Sox10, and were negative for Cytokeratin-AE1/ AE3. Based on these aspects, the final diagnosis was malignant S281