ECP 2023 Abstracts

S214 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Background & objectives: The routine histopathological examination of sleeve gastrectomy specimens taken as part of weight management strategy often yields pathological diagnoses, even in the absence of macroscopic pathology. We aim to identify the incidence of micro- scopic pathology in sleeve gastrectomy specimens. Methods: We reviewed the histopathology reports for all sleeve gas- trectomy specimens received into the Royal Oldham Hospital Cellular Pathology department within a 12 month period (2021) and recorded patient age, gender and final diagnosis. Results: Sixty nine sleeve specimens were identified for review. 96% of patients undergoing sleeve gastrectomy procedure were female and the mean age of all patients was 42 years. Thirty seven (53.6%) showed no significant abnormality. Pathological findings were identified in thirty two (46.4%) with a range of diagnoses identified, including; Helico- bacter Pylori (HP)-negative gastritis (16 [23.2%]); Reflux (10 [14.5%]); HP gastritis (3 [4.3%]); fundic gland polyp (1 [1.4%]); leiomyoma (1 [1.4%]) and gastrointestinal stromal tumour (1 [1.4%]). Of the thirty two cases with pathological diagnoses, thirty (93%) had diagnoses that would potentially require post-surgical treatment/management. Conclusion: Given the number of treatable diagnoses identified at histopathological examination, we conclude that histopathological examination of sleeve gastrectomy specimens remains an important procedure for post-surgical treatment/management. E-PS-06-084 The role of H. pylori infection and mast cells in the pathogenesis of inflammatory changes in the gastric mucosa I. Sertakov*, V. Shishkina, A. Filin, V. Aralova *Voronezh State Medical University, Russia Background & objectives: Mast cells (MC) are one of the key promot- ers in the regulation of the cascade of inflammatory mediators and the formation of an inducible type of cytokine expression. Mast cells have a wide arsenal of biologically active substances. Methods: Gastrobioptates of 19 patients with unknown H. pylori infec- tion status were studied. IHC with antibodies to tryptase and H. pylori was performed. The determination of the amount of tryptase-positive MC was carried out using a planimetric analysis in the field of view. The numerical values obtained were recalculated to obtain quantitative data reflecting the density of MC distribution per mm2. Results: H. pylori infection was detected in 63% of cases. The num- ber of tryptase-positive mast cells was significantly higher in patients infected with H. pylori . Mast cells in the presence of H. pylori showed intensive degranulation. Double immunofluorescence labelling of tryptase MC and H. pylori : clusters of large free-lying granules around glands with a pronounced degree of H. pylori contamination, inten- sive infiltration of epithelial cells of the gastric mucosa by mast cells and their granules in patients with H. pylori . Activation of tryptase expression was observed (correlating with an increase in the severity of the inflammatory component of the gastric mucosa in patients with Nu pylori to a much greater extent relative to uninfected patients). Conclusion: The role of mast cells in this process is ambiguous, it depends on many factors and features of the cellular microenvironment, the degree of damage to the mucous membrane and the duration of the inflammatory process. The polyfunctionality of tryptase makes it possible to more fully reveal the importance of mast cells in the devel- opment of both adaptive and pathological reactions during molecular morphological analysis. E-PS-06-085 Undifferentiated oesophageal carcinoma with sarcomatoid mor- phology: a case report and short literature review E. Souka*, G. Galanopoulos, G.M. Stanc, P. Bafaloukos, S. Xinoga- los, O. Tzaida *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Undifferentiated oesophageal carcinoma (UEC) is a very rare neoplasm. It’s characterized by an expansile growth pattern of neoplastic cells organized in solid sheets, without significant glandular, squamous, or neuroendocrine differentiation, occasionally adopting a sarcomatoid or rhabdoid morphology. Methods: A 55-year-old patient presented to the gastroenterology department with solid food dysphagia and weight loss. The endoscopy revealed a large obstructing polypoid oesophageal mass measuring 3cm. Subsequently biopsies were obtained. CT imaging showed no definite metastatic disease. Results: Microscopically, the oesophageal mucosa was infiltrated by a high-grade neoplasm composed of highly pleomorphic cells with abundant giant and multinucleated bizarre forms diffusely arranged in a loose stroma. The epithelium was almost completely ulcerated, except of a few strands of intact non-neoplastic squamous epithelium. The immunohistochemical examination revealed the following immunophe- notype: CKAE1/AE3+, CK8/18+, CK7-, p40+ few cells, Vimentin+, Chromogranin A-, Synaptophysin-, SMA-, Desmin-, c-Kit-, LCA-, CD30-, MelanA-, HMB-45-, S-100-, Ki67(MIB-1) up to 100%. The differential diagnosis included undifferentiated carcinoma, sarcoma, anaplastic lymphoma, GIST and melanoma. The final diagnosis was UEC with sarcomatoid-like morphology. Conclusion: The prevalence of UEC ranges from 0.15% to 4.5%, likely due to lack of definite diagnostic criteria. Its’ prognosis is poor, since 1-year survival rate is < 30% after esophagectomy, in comparison to >60% for stage III adenocarcinomas. Given that UEC is a very aggres- sive carcinoma, an accurate pathological diagnosis is of a great clinical value. UEC shares common epidemiological background with conven- tional adenocarcinoma, but more research is needed to elucidate its’ true origin, as well as optimal treatment. E-PS-06-086 Skin metastasis of oesophageal gastrointestinal stromal tumour. A potential pitfall H. Trihia*, E. Souka, G.M. Stanc, P. Bafaloukos, A. Mavrogiorgis *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Gastrointestinal stromal tumours (GISTs) metastasize mainly to liver and abdominal cavity. Metastases extra- abdominally occur in bone, pleura and soft tissue. Skin metastasis (SM- GIST) occurs in approximately 1% of advanced patients, with head, face and extremities been the most common sites. Methods: A 77-year old male with history of liver echinococcosis, underwent exploratory surgery. Intra-operatively, was diagnosed with oesophageal GIST, with simultaneous bone metastases and small liver nodules seven years postoperatively. Two years later, there was progres- sion of liver metastases. Concurrently, a recent skin nodule of 7mm of the scalp was excised. At the time of excision, medical history was not known. Results: Histological examination revealed a spindle cell lesion in short fascicles, with occasional mitoses, located in the dermis and upper sub- cutaneous fat. As the medical history was not known at the time, several immunostains were used, of skin spindle tumours, as the differential diagnosis of SM-GIST is a diagnostic challenge in which the morpho- logical differential diagnosis is broad and includes primary and meta- static tumours. After insisting for the medical history and consulting personally the patient and being informed of the GIST diagnosis, the implementation of DOG1, CD117 and CD34, established the diagnosis of SM-GIST. Conclusion: The mean postoperative time for GIST distant metastases is 2 years. At the time of diagnosis, up to 20% have developed metas- tases. The mean time to SM-GIST is 4.22 years, as unlike carcinomas which sometimes initially metastasize to the skin, SM-GIST is the late manifestation of disseminated disease. Therefore, SM-GIST should always be in consideration in case of even small and easily ignored skin