ECP 2023 Abstracts

S209 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 and histopathological characteristics of the cases found were analysed and compared with the findings found in the literature. Results: 10 cases with the presence of intestinal spirochaetosis were obtained. Six of them had concomitant sexually transmitted diseases. Histologically, with hematoxylin and eosin staining, areas of fraying of the epithelial brush-like luminal border were observed in all samples. In all cases, the Warthin-Starry and Spirochete histochemical and immu- nohistochemical techniques were requested. In nine of them the bacteria were clearly identified by both techniques, with diffuse involvement. In eight patients, spirochetes were found not only in the superficial epi- thelium but also in the crypts, also identifying, and exclusively in these same cases, lymphoid aggregates in the upper third of the lamina propria. Conclusion: It is interesting to note that our review and through histo- chemical and immunohistochemical techniques revealed the presence of spirochetes not only in the superficial epithelium but also within the crypts, coinciding in these cases with the presence of lymphoid aggregates. However, these findings did not have a correlation in terms of the degree and type of inflammation present in the lamina propia or in terms of the type of clinical presentation. E-PS-06-064 Differences in immunohistochemical expression of filaggrin between proton pump inhibitor-non‑responders and proton pump inhibitor-responders of eosinophilic oesophagitis R. Maruyama*, N. Ishimura, A. Araki, M. Yuki, N. Nagano *Izumo Tokushukai Hospital, Japan Background & objectives: The patients with eosinophilic oesophagi- tis (EoE) are divided into proton pump inhibitor-non-responders (PPI- NR) and proton pump inhibitor-responders (PPI-R). Our objective was to seek the clinical usefulness of the differences of barrier protein expressions between these two groups. Methods: Thirty PPI-NR, 45 PPI-R and 35 reflux oesophagitis patients were enrolled. After clinical information including age, gender and allergic backgrounds and histopathological findings were reviewed, immunohistochemical expressions of epidermal differential complex proteins (filaggrin, loricrin and involucrin) and desmoglein in all three groups were examined and semi-quantitatively scored. These clinical and pathological factors were statistically analysed between the three groups. Results: There were significant differences in age and gender between EoE and RE, but no differences were observed between PPI-NR and PPI-R. Regarding allergic conditions, the prevalence of asthma was significantly higher in PPI-NR than in PPI-R. Other allergic condi- tions showed no differences between the three groups. Conventional histopathological findings (number of infiltrating eosinophils, basal cell hyperplasia and spongiosis) did not exhibit statistical differences between PPI-NR and PPI-R. However, immunostaining score of filaggrin in PPI-NR was significantly lower than in PPI-R, although the expressions of involucrin, loricrin and desmoglein showed no differences. Conclusion: In the present study, we have demonstrated for the first time that the immunohistochemical expression of filaggrin in PPI-NR is significantly lower than in PPI-R. The results suggest a role of reduced filaggrin expression in the difference of effectiveness of PPI treatment between PPI-NR and PPI-R. Moreover, immunohistochemical deter- mination of filaggrin expression in EoE patients could be informative in clinical decision of how to treat the patients. E-PS-06-065 An exceedingly rare case of anorectal mucosal melanoma: case report M. Matanie*, A. Birceanu, M. Florescu, A. Martiniuc, N. Copca, M. Sajin, A. Evsei *Colentina Clinical Hospital, Romania Background & objectives: Anorectal mucosal melanomas (AMM) are exceedingly rare, generally present at a later stage, are more aggressive and carry a worse prognosis. We report a recent and rare case of AMM. Methods: A 77 years old patient presented to our clinic with rectal bleeding, chronic constipation, loss of appetite and a recent episode of sub occlusive colonic syndrome. On rectal examination a 2,5 cm, expan- sile mass and external haemorrhoids were noted. Colonoscopy revealed a fungating, circumferential, ulcerated mass and a rectal pedunculated polyp. No clinical history of cutaneous melanoma was found. Results: Multiple biopsies were performed, and histological examina- tion showed a solid proliferation composed of sheets of large pleomor- phic cells with prominent nucleoli, amphophilic cytoplasm and large amounts of intracytoplasmic brown pigment granules which were con- firmed to be melanin granules using Fontana-Masson staining. Excision of the mass and the rectal polyp revealed the same histological features. Tumour cells expressed SOX10 and S100. A diagnosis of AMM was established, and the patient underwent surgery for rectal amputation that histologically revealed a scar and residual tumoral cells in the submucosa and muscularis propria with no lymph node metastasis. Conclusion: Mucosal melanoma typically arises in the anorectal region, the median patient age at diagnosis is 65 years and accounts for less than 1% of gastrointestinal malignancies and 1% of anorectal malignancies overall. It shows a low mutation burden, with no UV signature. As in our case, the diagnosis is made in late stages. Pri- mary melanoma of the GI tract is an aggressive and clinically com- plex malignancy which remains associated with poor overall survival despite the use of multiple treatment modalities. E-PS-06-066 Gastric adenomatoid tumour – case report and literature review G. Miranda*, O. Pedro, J. Dos Santos, R. Machado-Neves, T. Amaro *Unidade Local de Saúde de Matosinhos - HPH, Portugal Background & objectives: Adenomatoid tumour is a rare benign neoplasm of mesothelial origin with predilection for the genital tract. Extragenital locations are rare and constitute a challenge in the dif- ferential diagnosis with malignant neoplasms. Description of a gastric adenomatoid tumour and literature review. Methods: The tumour was incidentally found in a 69-year-old woman undergoing hiatal hernia repair. During the surgical procedure, a poly- poid lesion was identified on the serosa of the anterior gastric wall, which had not been described by imaging methods. The lesion was sent for histopathological study. Results: Macroscopically, a polypoid lesion measuring 7 x 6 x 3 mm with a whitish cut surface was observed. On histological examina- tion, a neoplasm with circumferential but poorly defined boundaries was observed in a subserosal location, composed of tubules and tra- beculae of varying sizes. The neoplastic cells were flattened to cuboidal with moderate and eosinophilic cytoplasm, sometimes vacuolated. No mitoses or atypia were observed. The mesothelial nature of the lesion was confirmed by immunoreactivity for AE1/AE3 cytokeratins, cal- retinin, and WT1. Conclusion: Given their rarity, gastrointestinal adenomatoid tumours can represent a significant diagnostic challenge, especially in tumours with glandular and signet-ring morphology, mimicking primary or met- astatic adenocarcinomas. This distinction becomes crucial in the man- agement of the patient given the benign nature of adenomatoid tumours. E-PS-06-067 Chronic radiation enteritis with diffuse ganglioneuromatous pro- liferation - a rare association presenting as subacute intestinal obstruction S. Naresh Shah*, A. Parameswaran *Apollo hospitals, India