ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 73.7% (14/19); GATA3+ 46.7% (7/15); GCDFP15+ 90% (9/10); P40, S100 and Melan-A all negative (21/21, 24/24 and 20/20). However, 5 visceral-EMPPDs were previously misdiagnosed as skin origin when CDX2 was not accessed, 1 of them with invasive mixed neuroendo- crine non-neuroendocrine neoplasm (MiNEN) component that required additional chemotherapy treatment. Four skin-EMPPDs were originally called viscerally-originated when GATA3 was not accessed. Adding GATA3 and CDX2 to the most used CK7/CK20 panel illustrated true disease origins (skin versus visceral) and impacted clinical courses. GCDFP15 was less sensible than CK7 to identify EMPPD. P40, S100 and Melan-A show no diagnostic value. Conclusion: EMPPDs have underrecognized malignant potential. The immunohistochemical panel CK7/CDX2/GATA3/CK20 that we propose refines EMPPD diagnosis by highlighting its origin(s), therefore providing new opportunities for patients’ stratification and clinical management. E-PS-06-065 A rare case of concomitant RAS and BRAF mutation in colon adenocarcinoma J. Gama*, A. Gomes, P. Teixeira, J. Madeira, C. Faria, V. Almeida, F. Ramalhosa, G. Fontinha, B. Sepodes, C. Courelas, A. Alves, R. Oliveira, M.A. Cipriano *Centro Hospitalar e Universitário, Portugal Background & objectives: Colorectal cancer is one of the most com- mon cancers worldwide. RAS and BRAF are key oncogenes in the RAS/RAF/MAP-kinase pathway. RAS mutations are predictive of resistance to anti-EGFR drugs. RAS and BRAF mutations are gener- ally recognized to be mutually exclusive. Methods: An 87-year-old man presented to the emergency service with complaints of breathlessness, fatigue and anaemia. During the hospitalization, a colonoscopy was performed. An exophytic and ulcerative tumour was found in the right colon. Biopsies were performed and the diagnosis of a colic adenocarcinoma was made. The multidisciplinary tumour board decided to perform a right hemicolectomy. Results: On gross examination, a tumour with 6.8x5.2cm which obliterated the colic lumen was described. Histologically it had a tubular and glandular architecture, with a mucinous component that represented 60% of the neoplasia. One, out of thirty one, lymph nodes was metastasized. Loss of MLH1 and PMS2 was detected by immunohistochemistry, MSH2 and MSH6 expression was maintained. The pathological stage was T3N1M0. The mutational status of the RAS and BRAF genes was studied by PCR. The mutation p.Gly12Ala/p.Gly12Val(G12A/V, c.35G>C / c.35G>T), was detected in codon 12 of the NRAS gene. In the BRAF gene the mutation V600E/D(c.1799T>A; c.1799_1800delinsAA/ c.1799_1800delinsAC) was detected. Conclusion: A concomitant BRAF and RAS mutation is very rare, with an estimated incidence of 0.05%. As a rare event not much is known about the appropriate treatment and prognosis of these patients, which seems variable. Prospective studies in a large cohort are needed to fully understand the characteristics of this subset of patient with colon cancer. E-PS-06-066 Clinical and pathological features of the major duodenal papilla lesions K. Ben Abdallah, F. Khanchel, S. Elfekih*, H. Zaafouri, M.K. Tounsi, I. Helal, R. Hedhli, E. Ben Brahim, D. Trad, R. Jouini, A. Chadli *Habib Thameur Hostpital,Tunisia Background & objectives: Ampullary carcinomas are a rare entity accounting for 0.2% of gastro-intestinal cancers. They arise from ade- nomatous lesions presenting each a different malignant potential. The aim of our study was to determine the characteristics of ampullary lesions in our population study. Methods: Clinical, endoscopic, radiological and pathological features of 47 Patients who underwent upper GI endoscopy with biopsies of the major papilla or surgical resections (pancreaticduo- denectomy) over the last 20 years were collected and statistically analysed. Results: Mean age was 62.65 years. Side-viewing endoscopy identified an irregular protrusion in lumen in most cases (27.7%). ERCP identified bile duct invasion in 8.5% of cases. Three patients had metastatic disease. Lesions were adenocarcinomas in 74.5% of cases, adenomas in 17% of cases, among them 65.2% high grade. Unspecific inflammation was found in 8.5% of cases. Pancreaticobiliary type represented 36.3% of adenocarcinoma, 5% were intestinal type, 31% of mixed type adenocarcinoma, one case of mucinous carcinoma and one patient had an undifferentiated carcinoma with giant osteoclast-like cells. Tumours were well differentiated in 73.5% of cases. 65.5% of tumours were stages I/II. Conclusion: Ampullary lesions are dominated by adenocarcinoma and most of them are stage I/II. In fact, ampullary carcinomas are generally symptomatic at an early disease stage, thus, withholding a better prognosis than other periampullary cancers. Early management of ampullary neoplasms can prevent malignant transformation. E-PS-06-067 Constitutional mismatch repair deficiency as a differential diagnosis of neurofibromatosis type 1 – a case report D. Enea*, P. Benigni, A. Sayadi, C. Groulez, M. Svrcek *Sorbonne Université, AP-HP, Saint-Antoine Hospital, Department of Pathology, Paris, France Background & objectives: Constitutional mismatch repair deficiency (CMMRD) syndrome is a childhood cancer predisposition syndrome that results from biallelic germline mutations in one of the MMR genes. The tumour spectrum is very broad and the benign manifestations can mimic neurofibromatosis type 1 (NF1). Methods: A 15-year-old boy, with no recorded family medical history, presented with multiple café-au-lait macules, mainly local- ized on the anterior abdominal wall, and severe iron-deficiency anaemia. During the hospitalisation, his condition worsened expe- riencing gastro-intestinal symptoms with signs of intestinal intus- susception. A priori detailed examination led to a right colectomy being performed. Results: Macroscopic examination of the resected specimen revealed four polyps (4mm, 15mm, 30mm, and 40mm, respec- tively). Histologically, they all represented tubular/tubulo-villous adenomas, out of which the three largest presented high-grade dys- plasia; foci of carcinoma in situ/intramucosal adenocarcinoma were observed in the 40mm polyp. Consequently, immunohistochemical stains for the MMR proteins (MLH1, MSH2, MSH6 and PMS2) were performed, which demonstrated a loss of PMS2-protein in both tumour and non-neoplastic tissue. The technique was repeated yielding the same results. The patient’s young age, the NF1-like features and the large tubulo-villous adenomas featuring carcinoma in situ were consistent with CMMRD. Moreover, a NF1 germline mutation was not detected, and further genetic analysis is expected. Conclusion: Despite the very low frequency of CMMRD, one should keep in mind the possibility of this diagnosis, as shown herein. Since skin café-au-lait spots are typically associated with NF1, a more frequent syndrome, CMMRD could be overlooked S234