ECP 2023 Abstracts

S248 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 was also found in the right III lymph nodes. Immunohistochemically, the atypical cells were positive for CD20, CD79a, CD30, PAX5, bcl- 2, bcl-6, MUM-1, and EBER (ISH), while being negative for CD10, CD15 and c-myc. Conclusion: Based on these pathological features, we diagnosed this tumour as EBV-positive DLBCL. In addition, neoplastic cells were weakly positive for CD3 and CD5, suggesting unusual expressions. It is noteworthy that, while extremely rare, EBV-positive DLBCL can occur in the thyroid and, from the diagnostic and therapeutic perspec- tives, differentiation from carcinoma, particularly ATC, is challenging. Therefore, it is worth considering this condition if a patient, especially one who is elderly, presents with a tumour showing rapid enlargement in the neck region. Funding: Tomonori Kawasaki was supported by Grants-in-Aid for Sci- entific Research (Nos. 21K06910, 20K08131 and 23K11869) from the Japanese Ministry of Education, Culture, Sports, Science and Tech- nology, Joint Research Support Grants based on the Comprehensive Agreement between Saitama University and Saitama Medical Univer- sity (22J01 and 21J14), and the National Hospital Organization (NHO) Grant (H29-NHO-01). E-PS-09-014 The adrenal rush: a single institute experience A. Lakshmanan*, R. Uthayasuriyan, N. Mulchandani, S. Naresh Shah, M. Menon, A. Subramanyam *Apollo Hospitals, India Background & objectives: Adrenal neoplasms are uncommon and often pose diagnostic challenges. They can be primary or secondary neoplasms. The objective of this study is to analyse the frequency and distribution of various adrenal neoplasms and highlight the existence of few rare cases. Methods: This is a retrospective study done over a period of 10 years (2011-2020) in the Department of Pathology, Apollo Hospitals, Chen- nai. Hematoxylin and eosin-stained sections and immunostains were reviewed and analysed. Results: A total of 320 cases of adrenal lesions were observed dur- ing the study period. Seven cases were excluded as the material was inadequate for further immunohistochemistry studies or for a definitive diagnosis. There were 277 primary adrenal neoplasms, 36 secondary neoplasms and 12 cases of adrenal haemorrhage. Adenoma was the commonest adrenocortical neoplasm and phaeochromocytoma was the commonest adrenal medullary neoplasm. Fourteen cases of dif- fuse large B-cell lymphoma were also noted. A variety of benign and malignant mesenchymal neoplasms were noted in 86 cases including rare entities such as solitary fibrous tumour, Ewing sarcoma and lipo- sarcoma. Secondary neoplasms included direct infiltration from other organ malignancies and metastatic carcinoma. Conclusion: This study highlights a broad spectrum of adrenal neo- plasms including a few rare unusual cases. Our case distribution fairly correlates with other studies in the literature. Meticulous grossing with careful histopathological evaluation supplemented by immunohisto- chemistry is required in arriving at the correct diagnosis of rare entities. E-PS-09-015 Thyroid carcinoma in children, adolescents, and young adults: a retrospective evaluation on 88 cases in 10 years period V. Macarrón Aguilera*, M.E. Brizzi, A. Carcavilla, J.C. Moreno-Nav- arro, M.I. Esteban-Rodríguez, R.M. Regojo-Zapata *La Paz University Hospital, Spain Background & objectives: Paediatric thyroid cancer is a current area of interest with few studies and has distinct features from thyroid can- cer in adulthood. Our aim is to evaluate thyroidectomies performed in in our centre for the last 10 years in this population. Methods: All thyroidectomies performed in patients under 33 years in a tertiary referral hospital between January 2013 and April 2023 were identified. Clinicopathological features were extracted from the electronic medical records, including gender, age and histological diagnoses. Cases since 2017 also included molecular studies. Results: Of 225 thyroidectomies performed (168 women and 57 men, with a median age of 24.13 years), 88 presented a thyroid carci- noma (39,1%). Papillary carcinoma (PTC) was diagnosed in 82 cases (93,2%). Molecular studies were conducted on 47 cases, finding 26 cases (55,3%) with BRAF V600E mutation. Moreover, 5 RET rear- rangements (10,6%) and 1 (2,1%) NTRK fusion gene were identified. One case (2,1%) presented a syndromic familial follicular cell-derived thyroid carcinoma (DICER1 syndrome). Minimally invasive follicular carcinoma were identified in 3 cases (3,4%). Finally, 3 cases (3,4%) of medullary carcinoma were diagnosed in prophylactic thyroidectomies performed due to a germline RET mutation. Conclusion: In our cohort, PTC is the most common malignancy with BRAF V600E mutation in half of the cases. RET and NTRK fusions should be tested in negative BRAF V600E cases to facili- tate the selection of patients for developing molecular targeted therapies. Patients with thyroid cancer predisposition syndrome should be detected for special oncological management and care. More regional and national studies are needed to better understand this pathology, and to develop diagnostic and therapeutic guide- lines for this population. E-PS-09-016 Disseminated neuroblastoma with initial presentation as a man- dible mass in a child N. Martínez Arnau*, I. Marquina Ibáñez, S. Hakim Alonso, J. Alfaro Torres, J.L. Delgado Fernández, J. Martínez Castillón, L. Ollero Domenche, A. Carilla Sanromán *Hospital Universitario MiguelServet, Spain Background & objectives: Neuroblastoma is a relatively common malignancy of childhood. However, when it debuts in a not typical location the diagnosis is difficult because its radiology image and symptoms suggest other kind of lesions. Methods: We report a case of an 11-year-old child with a solid and painless lesion of 25 mm located in the right jaw branch affecting soft tissues. Clinically, seemed an inflammatory process or adenopathy and radiology suggested a mandible sarcoma. Results: The lesion was biopsed. Several yellowish-brown fragments measuring 16 mm were received. Histological examination revealed bone fragments and skeletal muscle infiltrated by a neoplasm com- posed of sheets and cords of small round cells with hypercromatic nuclei and stretching artefact. Neoplastic cells expressed immunohis- tochemically synaptophysin, CD56, vimentin and chromogranin with negativity of CKAE1AE3, CD45, S100, CD99, CD34, actin, desmin, WT1 and FLI1. Proliferative index with Ki67 was 95%. Based on mor- phology and immunohistochemical profile, the lesion was diagnosed as metastasis of neuroblastoma. Given these results, further image studies were made. An adrenal mass with multiple distant metastasis was found, with neuroblastoma as a result of the biopsy. Conclusion: Neuroblastic tumours are the third most common child- hood neoplasms after leukaemias and brain tumours. Therefore, we must think of them whenever the patient is a child, no matter the start- ing location we have. E-PS-09-017 Follicular cell-derived thyroid carcinoma following tyrosine kinase inhibitor treatment S. Molés Caparrós*, A. Veliz Dominguez, J.C. Corredor-García, T. Alonso-Gordoa, B. Porrero-Guerrero, H. Pian-Arias, I. Ruz-Caracuel *Ramón y Cajal University Hospital, Spain