ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 including 23 (26.74%) cases with dysplasia: 21 patients with low-grade and 2 patients with high-grade dysplasia. Non-IM was observed in 56 patients: 30 cases of cardiac type metaplasia and 26 cases of oxynto-cardiac metaplasia. Dysplasia was identified in 2 patients (3.57%), both high-grade dysplasia on background of cardiac type metaplasia. Dysplasia was never found on background of oxynto-cardiac metaplasia. Conclusion: In our single centre experience, incidence of dysplasia was much higher in patients with IM compared with non-IM of distal oesophagus (Fisher exact test, p = 0.0024), which is con- sistent with generally accepted concept of carcinogenesis in distal oesophagus. Nonetheless, rate of high-grade dysplasia didn’t differ between groups (Fisher exact test, p = 0.6496). Almost 1/5 of cases with columnar-lined oesophagus was challenging for metaplasia type identification and required immunohistochemistry with Muc2. Majority of these cases appeared to be non-IM. E-PS-06-010 Immunohistochemical evaluation of diffuse gastric cancer mor- phological variants L. Mikhaleva*, K. Midiber, K. Maslenkina, A. Biryukov, Z. Gioeva *A.P. Avtsyn Research Institute of Human Morphology, Russia Background & objectives: Transcriptome analysis revealed distinct subtypes of diffuse-type gastric cancer (DGC): DGT arising de novo and DGT originating from intestinal-type gastric cancer (IGC) cells. The aim of our study was to develop morphological and immunohis- tochemical criteria for subtyping of DGT. Methods: Fifty patients with DGC were included in the study. DGT was established based on morphological exanimation of specimens stained with haematoxylin and eosin and combined PAS/AB for signet- ring cells identification. Immunohistochemical study was performed with E-cadherin, CK7, CK20, CDX2, Hepatoc, Muc1, Muc2, Muc5AC, HER2, PD-L1. Monoclonal antibodies to MSH2, MLH-1, PMS-2 and MSH6 we used for microsatellite instability (MSI) detection. Results: Four patients were HER2 positive, two patients were indefinite for HER2. PD-L1 staining results were the following: Combined Positive Score (CPS) was >1, but <10 in 4 cases, CPS >10, but <20 in 2 cases and CPS = 100 in one patient. MSI-High was detected in 2 cases and MSI-Low in one patient, both patients harboured MSH6 mutation. All patients with MSI were of higher age (> 75 years). There were no significant differences in immu- nophenotype using extensive antibody panel, but we noticed some features in mucin profile special for MSI. Further investigations are needed to confirm our findings. Conclusion: No significant immunophenotype features special for different morphological subtypes of DGC were identified, but we suggest that further studies of mucin profile in patients with MSI are of value. We suppose that older age and MSI are indicative for DGT originating from intestinal-type gastric cancer. Whether mixed type gastric cancer may represent a transitional form between IGC and DGT remains a question. E-PS-06-011 Oesophageal squamous papillomatosis: a case report K. Ben Lazreg*, R. Jouini, I. Helal, F. Khanchel, R. Hedhli, S. Fkih, E. Ben Brahim, M. Sabbah, A. Chadli *Habib Thameur Hospital Pathology departement, Tunisia Background & objectives: Oesophageal squamous papilloma (OSP) is a benign uncommon papillary epithelial polyp with uncertain aetiology. It’s usually an asymptomatic solitary lesion of the lower oesophagus, commonly occurring in male adult. We report a rare case of Oesopha- geal papillomatosis (OP). Methods: 57-year-old women, with no medical history, presented with epigastric pain and two episodes of hematemesis. She under- went an initial oesophagogastroduodenoscopy (OGD) with biopsy. Subsequently, endoscopic follow-up with repeated biopsies was performed. Results: The OGD showed multiple circumferential pseudopol- ypoid formations, spread over 6 cm of the lower oesophagus. Elsewhere, the oesophageal mucosa was normal. Histological examination of biopsy specimens, showed a papillary exophytic proliferation of squamous epithelium, lining fibrovascular cores of lamina propria. The squamous epithelium presents focal parakera- tosis but does not exhibit dysplasia or evidence of viral infection. There was no invasion of the lamina propria. The final diagnosis was OP associated with hiatal hernia and chronic gastritis. Endo- scopic monitoring did not reveal any progression of lesions with similar pathological features. The decision of medical staff was to continue the endoscopic surveillance. Conclusion: Fewer than 20 cases of OP were reported in the Eng- lish literature. Symptoms, like bleeding or dysphagia, may be seen in papillomatosis. Chronic irritation and HPV infection are the most reported aetiologies in literature. The role of HPV infection is not well proved. Generally, the OSP does not recur after resection. However, OP has an unknown potential for malignant transfor- mation, with currently no guidelines for endoscopic surveillance. Therefore, more cases need to be published. E-PS-06-012 Granular cell tumour of the appendix – an extremely rare case report J. Madeira*, F. Ramalhosa, C. Faria, M.R. Silva, M.A. Cipriano *Serviço de Anatomia Patológica, Centro Hospitalar e Universi- tário de Coimbra, Portugal Background & objectives: Granular cell tumour (GCT) is a benign lesion of neural/schwannian origin most frequently found in skin, sub- cutaneous tissue and oral cavity mostly in black middle-age women. They can involve any organ, including the gastrointestinal tract. The appendicular involvement is extremely rare. Methods: We report a case of a 30-year-old pregnant female, recurring to the emergency department with two days persistent pelvic pain. The blood test indicated leukocytosis, neutrophilia and elevated concentration of C-reactive protein. Abdominal ultrasonography revealed an outer appendiceal diameter of 8mm, with markedly thickened and stratified wall and increased density of the surrounding fat tissue consistent with a phlegmon. Results: A laparoscopic appendectomy was performed. Gross examination showed appendiceal wall markedly thickened and the lumen filled with fecal material. Histological analysis revealed a florid granulomatous chronic inflammation in the tip of the appendix. Adjacent there was a well- circumscribed and uncapsulated nodule with 0.5cm in diameter confined to submucosa. It was formed by nests of epithelioid cells with abundant granular eosinophilic cytoplasm and central small round nuclei. It was devoid of cytological atypia and necrosis. Immunohistochemistry revealed S-100 diffuse strong positivity, suggestive of Schwann cell origin. Tumour also displayed SOX- 10 nuclear expression and CD68 membranous expression in the tumour and in granulomas found in the wall of the appendix. Conclusion: 5–11% of GCT occurs in gastrointestinal tract, with only fourteen cases reported in the appendix. Literature suggests that chronic inflammation surrounding the GCT in the appendix may be a predisposing condition, favoring its emerging. These S219