ECP 2023 Abstracts

S220 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Conclusion: This study reports novel data on the prognostic value of DPD staining intensity in lymph node metastases in pancreatic cancer. High expression of DPD is a negative prognostic factor and may indi- cate that more intense postoperative treatments and follow up programs are needed. Funding: FORSS (grant number 941207) County of Östergötland (grant numbers 962449 and 935580) E-PS-07-008 Hepatic inflammatory pseudotumour (HIP) as immune response adverse event (irAE) in a patient with large B Cell lymphoma treated with cancer immunotherapies (bispecific antibodies -Obi- nutuzumab and Glofitamab- and CAR-T). Z. Calixto Alvarez*, M. De Uribe Viloria, A. Hidalgo Romero, J.T. Zuñiga Gaitan, Á. Serna Pareja, X. Merino, M. Riveiro Barciela, M.T. Salcedo Allende *Vall d´Hebron Barcelona Hospital, Spain Background & objectives: HIP is a benign lesion with various aeti- ologies. Due to the absence of pathognomonic findings, it’s difficult differentiate it from neoplasms and histological analysis is necessary for diagnosis. We present a case of HIP as irAE associated to cancer immunotherapies. Methods: We present a 63-year-old asymptomatic patient with refrac- tory large B-cell lymphoma, who after receiving several immunothera- pies, was diagnosed with multiples liver lesions as probable progres- sion of the underlying disease on a follow-up CT scan. During a year, three liver biopsies of the lesions were made. Histological study with histochemical stains and immunohistochemistry, to rule out microor- ganisms and lymphoma, were performed. Results: All three hepatic biopsies showed sclerosing stroma with lymphoplasmacytic and histiocytic infiltrate and multinucleated giant cell. Immunohistochemistry confirmed the presence of CD3+ and CD8+ lymphocytes, CD68+ histiocytes, IgG4- and ALK-. All these findings were consistent with HIP. The surrounding liver parenchyma demonstrated acute necroinflammatory hepatitis with abundant eosinophils. No microorgnisms were observed with PAS, methena- mine silver and Ziehl-Neelsen stainings. The patient had a positive serology (IgG and IgM) for Coxiella, but PCR tests from biopsies were negative. The HIP remained stable or decreased in size when treatment was withdrawn and increased in size when immunotherapy was reintroduced, suggesting an association between cancer immu- notherapies and HIP as irAE. Conclusion: We present a case with histological confirmation of IPH as irAE associated with immunotherapies, in a disease-free patient during histological study course. Cancer immunotherapies have been associated with HIP as an uncommon irAE, that could be misdiagnosed with malignant neoplasms or infections. Because of improvement and complexity of these treatments, a multidisciplinary diagnostic approach is necessary to integrate clinical, radiological and histological findings to avoid over-treatment and identify irAE in early stages. E-PS-07-009 Hepatic vascular tumours: a diagnostic challenge in small biopsies. The role of morphological and immunohistochemical markers in the differential diagnosis J. Chabla Jaramillo*, T.M. Silva, C. Romagosa Perez-Portabella, A. Diazgranados Daza, A. Hidalgo Romero, X. Merino, C. Gómez Gavara, C. Dopazo, M. Caralt, S. Ramón y Cajal Agüeras, M.T. Sal- cedo Allende *Hospital Universitari Vall d’Hebron, Spain Background & objectives: Hepatic vascular tumours (haemangiomas, small vessels neoplasm (HSVN), epithelioid haemangioendothelioma and angiosarcoma) present heterogeneous histomorphology, making the diagnosis difficult in small biopsies. The purpose of this review is the comparison of the histomorphological characteristics and immu- nohistochemical techniques for diagnostic aid. Methods: We reviewed 12 cases of hepatic vascular tumours from 2019 to March 2023: five cases of haemangiomas (HM), four cases of HSVN, one case of epitheloid haemangioendothelioma (EHE) and two cases of angiosarcoma (AS), in surgical specimens as well as small biopsies. The diagnosis was made taking into account hematoxylin- eosin findings, immunohistochemical study (IHC), and clinical-radi- ological correlation. Results: In relation to histological findings, all cases of HM didn’t show pleomorfism, multilayer growth, mitosis or necrosis; 75% of HSVN presented focal pleomorfism, without mitosis, multilayering and necrosis, similar to EHE. In contrast, AS presented marked pleo- morphism, mitoses, multilayer growth and necrosis. In relation to IHC, HM had Ki67 < 3%, p53, GLUT1 and C-myc negative; HSVN had Ki67 <10%, with one case of 12% without clinical and radio- logical signs of malignancy after two years follow up, negative for p53, GLUT1 and c-Myc; EHE with Ki67 > 10 %, p53, GLUT1 and c-MYC negative; AS with Ki67% > 30%, p53, GLUT1 and c-Myc positive. Conclusion: The differential diagnosis between HSVN and AS is the hardest challenge, because of the partial representation of histomorpho- logical characteristics and the collapse artefact of these lesions in small samples. We conclude that the multilayering, presence of mitosis and necrosis are findings that can help for a certainly diagnosis of AS. The proposal of a Ki67 <10% for non-angiosarcomatous lesions is fulfilled, but less in one case. We must be cautious in small biospias due to the heterogeneity of the marker. E-PS-07-010 Intrahepatic immune cell profile of bariatric patients with non- alcoholic fatty liver disease and associations with disease severity L. Chen*, G. Araujo, K. Schwenger, S. Fischer, T. Jackson, A. Okrainec, J. Allard *Sunnybrook Health Sciences Centre, University of Toronto, Canada Background & objectives: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in developed countries with few therapeutic options. The pathogenesis of NAFLD is multifactorial and involves several immune-cell-mediated inflammatory processes, but the exact mechanisms causing inflammation and fibrosis remain enigmatic. Methods: 118 morbidly obese patients who underwent bariatric sur- geries were recruited and liver tissue samples were taken. Liver his- tology was assessed using the Brunt system: 41 patients with simple steatosis (SS), 42 patients with steatohepatitis (NASH) and 35 with unremarkable liver histology (MOC). The frequency, location and phenotype of 8 immune cell subtypes were analysed by multiplex immunofluorescence. Results: The numbers of helper T Cells, natural Treg cells, mac- rophages and B Cells significantly increase as disease progresses. The number of activated macrophages increases at the early stage of the disease and decreases in the stage of severe fibrosis. In addition, patients with simple steatosis have more cytotoxic T cells and NKT cells compared to healthy controls. Patients with NASH have less NKT cells compared to patients with simple steatosis. The numbers of NK