ECP 2023 Abstracts

S210 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Background & objectives: Chronic radiation enterocolitis can occur within days or after years in patients with history of radiation ther- apy for pelvic tumours. It occurs in about 20% of these patients, with obliterative arteritis causing intestinal ischemia, being the pathological process involved. Methods: A 71year old lady, with history of radiation therapy 25 years ago for cervical carcinoma, presented with subacute intestinal obstruc- tion. Radiological imaging revealed multiple ileal strictures with dif- fuse wall thickening. An emergency laparotomy was performed, and the bowel segment was sent for histopathological examination. Results: Grossly, there were four strictures with firm white wall thicken- ing, nodular mucosa with intervening ulceration. Histological examina- tion showed ulceration with inflammation, hyalinised vessels with fibro- intimal hyperplasia, stromal atypia and submucosal fibrosis. In addition to these findings, there was diffuse nodular transmural ganglioneuronal proliferation with Schwannian stroma. The features were suggestive of Chronic radiation enteritis with associated diffuse ganglioneuromatous proliferation. Patient had no genetic predispositions, no clinical signs/ lesion of Neurofibromatosis or any such syndromes on examination. Conclusion: We present a rare association of Chronic radiation enteri- tis with incidental diffuse ganglioneuromatous proliferation, probably first of a kind, the significance of which is not known. To the best of our knowledge, the presence of ganglioneuromatous proliferation has not been typically described as a part of radiation induced injury. E-PS-06-068 Low-grade appendiceal mucinous neoplasm (LAMN) and endome- triosis of the appendix in a 46-year old woman: a case report about an exceedingly rare disease association S. Neves*, F. Sousa Vieira, D. Sá, A.P. Rodrigues, J.R. Vizcaíno, N. Jorge Lamas *Centro Hospitalar Universitário de Santo António, Portugal Background & objectives: Low-grade appendiceal mucinous neo- plasm (LAMN) is a rare mucinous appendiceal neoplasm found in ~1% of appendectomies. Appendiceal endometriosis is only identified in <1% of patients with pelvic endometriosis. The co-existence of LAMN with appendiceal endometriosis has been scarcely reported. Methods: We report a case of a 46-year old woman who presented with abdominal pain in the right lower quadrant. The ultrasonography and computerized tomography scan studies showed an appendiceal mucocele. The patient was submitted to right hemicolectomy. Results: The surgical specimen comprised an ileum segment of 8 cm, cecocolic segment of 9 cm and an appendix of 10 cm, containing irregu- lar serosa, increased caliber, lumen with abundant mucinous content and an area of rupture reaching the mesoappendix. Histological analysis showed LAMN with only acellular mucin invading the subserosa and mesoappendix, accompanied by lesions of acute appendicitis. Besides, several foci of endometriosis involving the appendix wall were present, highlighted with CD10 and ER immunohistochemistry markers. The eight lymph nodes isolated were not involved by metastasis. The molecu- lar biology study (NGS and PCR) demonstrated a KRAS gene mutation. Cytological analysis of the peritoneal fluid did not show neoplastic cells. Conclusion: This case highlights the exceedingly rare occurrence of LAMN in the presence of endometriosis of the appendix. A more comprehensive knowledge on cases like this is needed to optimize the surgical approach and follow-up strategy. Three months have elapsed since the surgery and the patient remains well and alive, without any signs of disease recurrence. E-PS-06-069 Infective tumour like lesions of rectum and colon: a report of two cases M. Odida* *Department of Pathology, Faculty of Medicine, Gulu University, Gulu, Uganda Background & objectives: Malignant tumours involving colon and rectum are common in many countries. There are also some infective cases which may mimic tumours. We present here two infective cases which presented clinically as tumour. Methods: Two case reports of infective rectal and colonic lesions pre- senting clinically like tumours encountered during routine diagnostic histopathology. Results: Case 1. A 49 years old female presented with pain and bleed- ing an indurated ulcer of colon. A provisional diagnosis of rectal car- cinoma was made, and a biopsy was taken. Histological examination showed chronic inflammation with plasma cells and microgranulomas. The clue for the diagnosis was a penile ulcer biopsy from the husband which had the characteristic features of syphilis. Case 2. A 20 years old male came with history of abdominal distension and constipation for five days. A diagnosis of intestinal obstruction secondary to intestinal tumour was made and partial colectomy done. Histological examination of the mass showed chronic granulomatous inflammation containing Schistosoma mansoni ova. Conclusion: A number of infective lesions may present like tumours. Pathologists need to be aware of these unusual presentations. E-PS-06-071 The molecular nodal tumour load correlates with the size of the nodal metastasis in localised colon cancer patients B. Palomar De Lucas*, L. Alarcón, D. Mata, N. Tarazona, M. García, C. Martinez-Ciarpaglini *Incliva, Biomedical Research Institute, Hospital Clínico Universitario de Valencia, Spain Background & objectives: The nodal status is the major prognostic factor in colon cancer (CC). The TNM staging system includes the number of positive nodes regardless of nodal tumour load (NTL). We aimed at assessing the prognostic value of NTL in localised CC. Methods: Patients with localized CC were prospectively selected. We isolated lymph nodes (LNs) from the fresh adipose tissue and studied each one using two methods, the histopathological H&E evaluation and PCR (RT-LAMP, OSNA). We also estimated the NTL on H&E, based on the size of the tumour and the percentage of infiltration in each node. Results: 69 patients were included. The upstaging rate for early-stage CC patients after the analysis by OSNA was 7% (N=4). The molecular NTL significantly correlated with the pN stage (p = 0.000) but was not proportional to the number of affected LNs. Both the NTL and the H&E status correlated with the presence of lymphovascular invasion (p = 0.000) and extramural vascular invasion (p=0.011) however, only the NTL was significantly correlated with the presence of perineural inva- sion (p= 0.005) and the tumour budding grade (p=0.008). The NTL was significantly related to the size of the nodal metastasis (p=0.0005) and the percentage of the LN occupied by the tumour (p=0.0005). Conclusion: The molecular NTL evaluation is strongly related to poor prognostic factors in patients with localized CC. Although the NTL correlated with the size of metastasis, it was not proportional to the number of affected LNs, suggesting that the NTL provides different information than the TNM staging system. The prognostic value of the NTL will be analysed in our cohort after a longer follow-up. Funding: Project PI21/00695 financed by ISCIII and co-financed with FEDER funds E-PS-06-072 Pathomorphological evaluation of eosinophilic oesophagitis and reflux oesophagitis V. Pechnikova*, L. Mikhaleva, K. Maslenkina, E. Motylev, D. Atiakshin, G. Kudryavtsev, Y. Kudryavtseva, M. Gushchin, A. Konyukova, K. Midiber *Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution "Petrovsky National Research Centre of Surgery", Russia