ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 tests. For this reason, an MRI with contrast was indicated, which showed a lesion radiologically compatible with a cholangiocarci- noma. Therefore, a surgical resection was recommended in a mul- tidisciplinary committee. Results: The surgical specimen showed a hepatic parenchyma infil- trated by glandular structures with a tubular pattern, composed of atypical cells immersed in a desmoplastic stroma. It showed posi- tive staining for Q7, for low molecular weight (CAM5.2) and high weight (34Be12) keratins. Diagnosis was peripheral intrahepatic cholangiocarcinoma. Previously treated with first-line chemotherapy, in 2021 genetic variations on DNA and fusion genes on RNA were studied with the use of an expanded NGS panel. Mutations and amplifications on DNA results were negative, while results on RNA were not evalu- able. Therefore, a liquid biopsy was performed, detecting fusions of FGFR2-TACC2. In this instance, the patient benefited from a newly targeted therapy: FGFR2 inhibitor, Pemigatinib. Conclusion: Preservation and viability of the RNA is tough and decisive for appropriate/accurate analysis. Since FGFR2 partners are usually partially included in the commonly used NGS panels, plus the fact that the detection of fusion genes is technically hard, we conclude that this process is challenging. The role of liquid biopsy opens a new possibility to ensure the study of fresh material in order to improve the outcome of diagnosis. E-PS-07-025 A very rare tumour in gallbladder: coexistence of large cell neuroendocrine carcinoma and intracholecystic papillary neoplasm E. Dicle Serbes*, S. Sevim, S. Tamam, S. Culcu, A.E. Unal, S. Kiremitci *Ankara University Medical School, Pathology Department, Turkey Background & objectives: Neuroendocrine carcinomas(NEC) of gallbladder account for 0.5% of all NECs, 4% of all gallbladder malignancies. Large tumours often extend into liver and/or metastasize. Herein, we report an extremely rare case of NEC involving liver and gallbladder, accompanying intracholecystic papillary neoplasm(ICPN). Methods: We report a 62-year-old male patient presented with jaundice and abnormal liver tests. A solid mass involving liver and gallbladder was detected radiologically. PET/CT scan revealed also lung and skin metastases besides liver mass (SUVmax=16.3). His past medical history and physical examination was otherwise non- specific. Partial hepatectomy with cholecystectomy was performed. Results: Grossly, a tumoral mass with the largest diameter of 13.5 cm, extending between gallbladder and liver parenchyma was detected. A polypoid lesion in the mucosa was residing next to the tumour that was protruding into lumen. Histopathologically, main mass had solid-trabecular pattern, and composed of large atypical epitheloid cells with hyperchromatic irregularly-shaped nuclei, prominent nucleoli and granular cytoplasm. Geographic necrosis and frequent atypical mitotic figures were striking(21/10HPF). Tumour diffusely expressed synaptophysin and chromogranin with very high Ki67 staining(90%). Besides, mucosal polypoid lesion revealed a tubulopapillary growth exhibiting high-grade cytologic atypia. The main mass and the concomitant lesion were diagnosed as large cell NEC and ICPN with high-grade intraepi- thelial neoplasm. Conclusion: There are few publications in literature reporting NECs originating from gallbladder/biliary duct. However, another rare pathology, ICPN, was reported to have an increased associa- tion with NECs of gallbladder. In our case, though the tumour bulk of NEC was in the liver, presence of ICPN in close proximity with the tumour mass in the gallbladder raised a suspicion that the tumour may have originated from gallbladder. We thought the type of concurrence in our case is worthy of attention. E-PS-07-026 Solid pseudopapillary neoplasm of the pancreas in children: two cases of a rare entity C. Mora*, F. Santos, R. Fonseca *Serviço de Anatomia Patológica, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal Background & objectives: Solid pseudopapillary neoplasm (SPN) is a low-grade malignant tumour with a predilection for adolescent girls and young women. Although rare, it accounts for 60 to 70% of all paediatric pancreatic tumours, and usually has an excellent prognosis after surgical resection. Methods: Herein, we report the clinicopathological features of two cases of solid pseudopapillary neoplasm, along with a brief review of the literature. Results: Case 1 refers to a 13-year-old boy with a pancreatic head tumour and case 2 to a 14-year-old girl with a pancreatic uncinate process tumour, both presenting with abdominal pain. Cephalic duodenopancreatectomy was performed after a presumptive diag- nosis and confirmatory cytology, respectively. Grossly, tumours were 9cm and 3,6cm, well-demarcated, haemorrhagic, with solid and cystic areas. Microscopically, they were composed of poorly cohesive epithelial cells forming solid and pseudopapillary struc- tures, positive for β-catenin(nuclear), CD10, progesterone recep- tors and negative for chromogranin. No lymph node or distant metastasis were identified. Patient 1 is alive and disease-free for 6 months. Patient 2 developed a Wirsung duct stenosis, is alive and disease-free for 4 years. Conclusion: SPN is a rare low-grade malignancy often found inci- dentally or presenting with unspecific abdominal discomfort or pain. Awareness for this entity in the paediatric population and in males, along with the recognition of its morphological and immu- nophenotypical features are essential to confirm the diagnosis. As in the adult population, an excellent prognosis solely with surgery is described for paediatric patients, even in the presence of meta- static disease. E-PS-07-027 Two cases of hepatic epithelioid hemangioendothelioma with unusual TFE3 immunopositivity S.K. Dursun*, S. Güneş, Z.B. Erdem, B. Saka, F. Ozden, S. Erdamar, İ. Yilmaz, V. Adsay, N. Dursun Kepkep *Basaksehir Cam and Sakura City Hospital, Turkey Background & objectives: Hepatic epithelioid hemangioendothe- lioma (HEHE) is a malignant vascular tumour of the liver. There are 2 subtypes, conventional variant with WWTR1-CAMTA1 fusion and recently characterized variant with YAP1-TFE3 fusion which is extremely rare. Methods: We report two cases of HEHE which have striking morphologic features consistent with so-called YAP1-TFE3 fusion subtype, nuclear TFE3 expression and negative CAMTA-1 reactivity on immunohistochemistry. A 66 years old male and a 26 years old female with hepatic masses which were confirmed as HEHE on trucut biopsy. Results: Both patients have been treated with liver transplantation. Histological examination of the liver explant materials confirmed the presence of HEHE. Both had the unique histological features of S246