ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 cytoplasm and round nuclei with finely dispersed chromatin. Cel- lular atypia and necrosis were absent. Immunohistochemistry stains revealed the epithelioid cells to be positive for muscle specific actin, vimentin and CD34 and negative for epithelial markers, EMA, neuroendocrine markers and enolase, with low proliferative activity. S-100 and CD31 stains highlighted associated nerve fibres and endothelial cells lining blood vessels, respectively. Conclusion: Glomus coccygeum is a nonpathological structure whose incidentally observation may cause significant problems for pathologists unfamiliar with this lesion. According to the literature, its prevalence and functional significance are uncertain but its accurate diagnosis is important to avoid confusion with other sacral tumours. E-PS-06-027 Epidemiological, clinical, and pathological aspects of early gas- tric cancer in Tunisian people M. Triki*, M. Manai, S. Graja, M. Mellouli, L. Ayadi, W. Ghribi, T. Boudawara, R. Kallel *Department of Pathology, Habib Bourguiba University Hospital, Sfax, Tunisia Background & objectives: Early gastric cancer (EGC) is defined as being confined to gastric mucosa or submucosa. Its detection has increased in recent years due to advances in endoscopic techniques. Our aim is to analyse it’s epidemiological and clinico-pathological characteristics in Tunisian patients. Methods: We collected, during 30 years, 18 cases of EGC, diag- nosed in the department of pathology of Habib Bourguiba Hospital within the period lasting from January 1992 to December 2021. Results: The mean age at diagnosis was 57,8 years witha sex- ratio of 2. Fibroscopy showed an ulcerated aspect of the mucosa. The metastatic workup revealed inguinal lymphadenopaties in only one case. Patients underwent either total or sub-total gastrectomy. Median tumour size was 2,4 cm. It was mostly located in the lesser curvature (7 cases). Histologically, half patients had a carcinoma limited to the mucosa and the onther half had a carcinoma extend- ing to the submucosa. Helicobacter pylori infection was associated in 66,6% cases. Rate of lymph node metastasis was 0% in patients with adenocarcinoma confined to the mucosa, yet it was 44,4% in patients with carcinoma extending to the submucosa. Conclusion: Prognosis of EGC is excellent. The disease-free 5-year survival rate usually exceeds 90%. Patients with high risk of recurrence may be identified in relation with prognostic factors like histopatologic type, parietal extension and mainly lymph node invasion. Endoscopic mucosal resection can be indicated for EGCs confined to the mucosa having virtually no possibility of lymph node metastasis. E-PS-06-028 Clinicopathologic features of appendicular endometriosis: a retrospective case series of two university hospitals M. Bronte Anaut*, C.M. Vieru, J. Arredondo Montero, A. Larrea, T. Dot Gomara, A. Pasco, M.C. Llanos Chavarri, R. Guarch Troyas, M. Garcia Martos, A. Panizo Santos *Complejo Hospitalario de Navarra, Spain Background & objectives: Endometriosis is a benign gynecologi- cal condition. It sometimes appears in the appendix mimicking acute appendicitis or as an incidental finding in appendectomy specimens resected for other gynecologic or digestive pathologies, or other condi- tions of the appendix such as mucocele. Methods: The pathology archives of two University Hospitals were reviewed to search for cases with a diagnosis of appendicular endometriosis in a 20-year period (2000-2022). The slides were reviewed for microscopic data of interest. The medical records of the patients were reviewed for demographic and clinical data that might have some implication with this pathology. A descriptive statistical analysis was performed. Results: The sample was 105 women, age range 15-91 years (median 39.47). 64 patients had history of: endometriosis (21%), pregnancy/abortion (49.5%) and tumours (10.5%).70.5% presented as acute abdomen. Appendectomy was performed in the context of intestinal subocclusion in 9.5% cases.Endometriosis was mainly located at the tip (55.2%) followed by body and base. As for wall involvement in decreasing order: muscularis propria (50.5%), ser- osa and subserosa. The predominant type of endometrial stroma was atrophic along smooth muscle hyplerplasia. The most fre- quent accompanying histological findings were acute appendici- tis (41%) and periapendicitis (34.3%).No epithelial proliferative changes with atypia or malignant transformation were identified. In 16 patients, endometriosis was found in other locations (8.6% gynecologic, 6.7% ileal). Conclusion: Appendiceal endometriosis occurs in a wide age range. There is a high prevalence of previous gynecobstetric his- tory in affected patients. Clinically, the most frequent presentation of appendiceal endometriosis is acute appendicitis, thus it should be included in the differential diagnosis in women presenting with pain in the right iliac fosa. It can be found incidentally accompany- ing other pathologies. E-PS-06-029 Primary leiomyosarcoma of the stomach: a case report F. Ozden*, A. Cakir *Department of Pathology, Istanbul Medipol University, Turkey Background & objectives: Gastric leiomyosarcomas are extremely rare tumours. Few cases have been reported since the early 2000s, which can be considered the “post-CD117” era. It is thought that most of the cases reported before this period are gastrointestinal stromal tumours. Methods: A 72-year-old female presented with abdominal pain, loss of appetite, anaemia, and melena for the past 7 days. Gas- troscopy revealed a giant polypoid mass in the gastric fundus and body. Biopsies were obtained and reported as sarcoma with smooth muscle differentiation. PET/CT examination showed no suspicious metastatic lesions and the patient was treated with partial gastrectomy. Results: Macroscopic examination demonstrated a 12x9x4,5 cm protruding giant polypoid/nodular mass with a central necrotic depressed area. Microscopically tumour showed full-thickness invasion with both infiltrative and expansile borders and consisted of spindle-shaped atypical cells with brisk mitotic activity. There was 10 % of necrosis and up to 44 mitoses in 10 high-power fields. Immunohistochemically tumour cells were positive for SMA, Caldesmon, Calponin, and Desmin whereas CD117, DOG-1, CD34, MyoD1, Myogenin, S100, and ALK were negative. KI-67 prolif- eration index was 70%. There was no evidence of lymphovascular or perineural invasion. Surgical margins were free from tumour. The case was signed out as leiomyosarcoma, grade 3, and score 6 according to FNCLCC. Conclusion: Gastric leiomyosarcomas are rare tumours and the diagnosis can be challenging without immunohistochemical analysis like in resource-limited laborator ies. Even immunohistochemical findings can sometimes be confusing, as caldesmon, known to show smooth muscle differentiation, can be S224