ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 E-PS-06-045 HPV-associated mucoepidermoid carcinoma of the anal canal: a case report A. Fitouri, M.A. Bani*, P. Dartigues, S. Cotteret, J. Scoazec, A. Al Ghuzlan *Department of Medical Biology and Pathology, Morphological pathology laboratory, Gustave Roussy Cancer Campus, Villejuif, France / Paris-Saclay university, Gustave Roussy Cancer Centre, Inserm US23, CNRS UMS3655, AMMICa, Villejuif, France, France Background & objectives: Mucoepidermoid carcinoma (MEC) of the anal canal is rare. This type of tumour was first described in 1954, and a total of 58 cases have been reported. We herein report another case and emphasize on the immunohistochemical and molecular features. Met hod s : A 68 - ye a r- o l d woma n r e po r t e d d e fe c a t i on difficulties and self-discovery of an intra-anal swelling. Rectal ultrasound endoscopy revealed an hypo-echoic lesion of the anorectal junction measuring 17 mm in thickness with infiltration of the vaginal wall. The lesion involved the upper part of the anal canal and the internal sphincter. The patient had chemo-radiotherapy and an abdomino-perineal amputation was performed. Results: Microscopic examination revealed an infiltrative tumour composed of squamoid, mucin-producing, and intermediate- type cells, with a solid growth pattern. Tumour cells had large nucleoli with high grade atypia. There were no necrosis. Mucin was objectified by PAS, mucicarmin and Alcian blue stains. On immunohistochemistry, tumour cells expressed p63, p40, CK5/6, CK7 and p16. There was no expression of CK20, CDX2 and SATB2. In situ hybridization revealed the presence of high risk Human papillomavirus (HPV) RNA. The patient had adjuvant chemotherapy and relapsed after 6 months of surgery. Conclusion: Anal MEC is extremely rare and is characterized by the same phenotypical features aas MEC of other sites. This case report emphasizes the role of HPV in the oncogenesis of MEC. The prognosis remains poor despite the progress in the treatment of anal cancer. E-PS-06-046 Assessment of MMP9 expression in inflammatory bowel dis- eases (IBD) and microscopic colitis (MC) as a prognostic factor and a possible therapeutic target R. Ardeleanu*, A. Bastian, A. Cioroianu, D. Raduta, M. Matanie, A. Cernat-Stefan, S. Sabo, A. Ciocan, M. Filip, C. Popp *Colentina Clinical Hospital, Romania Background & objectives: Extracellular matrix remodelling through changes in the activity and expression of matrix metalloproteinases has known implications in the pathogenesis of inflammatory bowel disorders. We aim to review the correlation between MMP9 expression and disease severity in IBD and MC. Methods: This retrospective study included 20 cases out of which 6 with Crohn’s disease, 4 with ulcerative colitis, 8 with collagenous colitis and 2 with lymphocytic colitis. The MMP9 marker expression was evaluated based on positive lymphocytes from the inflammatory infiltrate in the lamina propria and the intraepithelial compartment using a four-tiered system: 0-none, 1-weak, 2- moderate and 3-strong positivity. Results: Out of the 10 cases with IBD, 33% had severe active disease with a mean positivity of 2,66 in the lamina propria and 2,33 in the intraepithelial lymphocytes and 25% had moderate active disease, the mean score being 2 in the subepithelial compartment and 1,5 in the glandular and surface epithelium. The rest of 42% had minimally active or inactive disease with a mean expression of 1,25 in lamina propria and 1,6 in the epithelium. Concerning the MC, the mean scores for the inflammatory infiltrate in lamina propria were 1,125 as opposed to 1,5 in the columnar epithelium in collagenous colitis and 1,5 versus 2,5 in patients with lymphocytic colitis. Conclusion: Etiology and pathological sequences in inflammatory bowel disorders are not fully understood, thus, emerging studies focus on different approaches as to predict the evolution and unveal personalized therapies. Stronger MMP9 expression in patients with IBD compared to MC, along with greater scores within higher severity cases than minimal or inactive stages of disease, strongly support the therapeutic potential of this marker and the use of its inhibitors for impeding aggravation or progression to adenocarci- noma, as suggested by other recent research. E-PS-06-047 Cystic mesothelioma of the peritoneum: a case report of an unusual tumour and litterature review O. Mnif*, R. Ayadi, E. Braham, M. Mlika, A. Rais, A. Ayadi, O. Ismail, F. El Mezni *Abderrahmen Mami Hospital, Tunisia Background & objectives: Cystic mesothelioma of the peritoneum is an uncommon, benign abdominal tumour. There have been fewer than 130 cases reported in the literature today. The diagnosis of this pathology is difficult and based on histological findings. We present a new case of this entity. Methods: We report the case of a 54-year-old women presented with abdominal pain and constipation. Abdominal examination was marked by diffuse abdominal distension, and tenderness. Computed tomography showed a large spherical multi-loculated cystic mass in the abdomen. Laparotomy was done. The mass and some of the free-floating cysts were carefully harvested. Benign cystic meso- thelioma was revealed in the pathology report. Results: 12 years later, she was operated on for gallbladder lithiasis. Intraoperative examination showed a cystic mass in the peritoneum. There was a significant peritoneal thickening, and a peritoneal effusion, with many cystic lesions that makes dissec- tion and resection very difficult. Gross examination showed Cysts filled with serous fluid and mesured 2,5x0, 5 cm. Microscopic examination revealed a numerous small cysts lined by a single layer of bland, flat to cuboidal cells. This cysts were separated by scant loose to collagenous stromal septa. No infiltrative invasion of underlying tissues. Chronic inflammation and haemorrhage com- mon. Immunohistochemistry stain showed that the tumour cells were positive for calretinin and WT1. Conclusion: Establishing a diagnosis of cystic mesothelioma of the peritoneum is a challenging task, given rarity of the disease and the small number of reported cases in the literature. This tumour is known for local recurrence. It’s agreed that surgery is the only effective treatment. E-PS-06-048 Paneth cell carcinoma: a rare subtype of gastric carcinomas S. Sengiz-Erhan, M. Gulluoglu, S. Erdogan-Durmus*, S.O. Aktas, A. Alemdar *Department of Pathology, Prof. Dr. Cemil Tascioglu City Hospi- tal, Istanbul, Turkey Background & objectives: Paneth cell carcinoma is one of the rare histopathological subtypes of adenocarcinomas arising from gastrointestinal tract. Several cases have been reported as individual case reports in the literature. S229