ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 in the spectrum of differential diagnosis when clinicians deal with chronic swelling of a joint. MRI findings are characteristic. Early synovectomy offers best functional outcome. E-PS-22-017 The cytotoxic properties of graphene derivatives and 2-metox- yestradiol / graphene compound on human melanoma (A375) and osteosarcoma (143B) cell lines A. Kamm, J. Gulczynski*, E. Izycka-Swieszewska, L. Lipinska, M. Gorska-Ponikowska *Dept. of Pathology and Neuropathology, Medical University of Gdansk, Poland Background & objectives: The objective was to assess and confirm cytotoxic properties of graphene derivatives (graphene oxide and reduced graphene oxide) and compound of 17-beta-estradiol metabo- lite with graphene on selected malignant cell lines with safety for the nonmalignant cells (fibroblasts). Methods: Human melanoma (A375), osteosarcoma (143B) and fibroblast (HDF) cell lines were incubated with 2-metoxyestradiol, graphene oxide and reduced graphene oxide solutions for 24 hours. Cytotoxicity as well as cell viability and proliferation potential was later assessed through MTT test and under microscope with additional immunostaining. Oxidative stress was analysed by Elisa assay. Results: Our in vitro studies confirm the stronger cytotoxic activity of 2-methoxyestradiol-graphene complexes compared to 2-methoxyestradiol sole activity against melanoma and osteosarcoma cells in analysed samples. The results are promising as we observe a selective cytotoxic effect on tumour cells, in contrast to normotypic fibroblast cells which remain intact. These results also show that there is no toxic effect in relation to healthy tissues, and that it is toxic in relation to neoplastic tissues, which is the goal of all oncological therapies. The mechanism of action of 2-metoxyestradiol/ graphene oxide is related to the induction of oxidative stress in malignant cells. Conclusion: Researchers are looking for substances efficient against malignancies and safe for the nonmalignant tissue. Cytotoxic properties of 2-methoxyestradiol and graphene derivatives were confirmed in separate in vitro tests against various malignancies. Graphene may be used as a carrier for other antineoplasmatic drugs, improves bioavailability, but its nanocomposite tags are also suitable for bioimaging and confirmation of drug delivery to the affected tissue as well. It all gives opportunity to use this type of materials in bio-nano- technology and personalized therapy. E-PS-22-018 Spindle cell lipoma with ossification mimicking atypical lipo- matous tumour/well-differentiated liposarcoma J. Ichikawa, T. Kawasaki, H. Imada*, A. Enomoto, N. Taniguchi, R. Tatsuno, S. Kanno, H. Haro *Saitama Medical University, Japan Background & objectives: Spindle cell lipoma (SCL) is a subtype of lipoma, but the characteristics of SCL are observed in both lipoma- tous and non-lipomatous tumours. In this article, we present a case of SCL with ossification mimicking atypical lipomatous tumours/well- differentiated liposarcomas (ALTs/WDLs). Methods: A 56-year-old man presented with a mass on the lateral side of the right distal thigh. Plain radiography showed a soft tissue mass with a high fat density and ossification. MRI revealed high and diffuse low signals on a T1-weighted sagittal image, heterogeneous low signal on T2 short tau inversion recovery images, and diffuse enhancement on gadolinium-enhanced T1-weighted axial image. Results: Needle biopsy findings suggested lipoma or ALT/WDL. Marginal resection with tumour capsule intact was performed. Macroscopically, the tumour was 8x5.5x2 cm in size, and the edge of the tumour was white owing to ossification. Histologically, the tumour consisted of ropey collagen bundles containing mature adi- pocytes and spindle cells without atypia. There was no fat necrosis in the tumour or malignant osteoid tissue in the ossified region. Immunohistochemistry showed positive staining for CD34, hetero- geneous deficiency in spindle cell, and positive staining in ossified region for RB1, and negative staining for MDM2 and CDK4. Fluo- rescence in-situ hybridization showed no amplification of MDM2. One year after surgery, the patient remains free of recurrence. Conclusion: We described an atypical case of SCL with ossifica- tion. SCLs are pathologically classified as classic, fibrous, myxoid, low-fat, pseudoangiomatous or fat-rich, and all 6 classes have vari- ous signals on MRI. Furthermore, differentiating between ALT/ WDL and SCL is challenging and clinically important. Consid- eration of all aspects of SCLs, including their clinical, imaging, histopathological, and especially immunochemical features, is the most comprehensive means of ensuring an accurate diagnosis. (Int J Surg Pathol, in press) Funding: Tomonori Kawasaki is supported by Grants-in-Aid for Scientific Research (No. 21K06910 and No. 20K08131) from the Japanese Ministry of Education, Culture, Sports, Science and Technology and the National Hospital Organization (NHO) Grant (H29-NHO-01). E-PS-22-019 A unique presentation of IgG4 related disease mimicking soft tissue tumour H. Imada*, T. Kawasaki, S. Kanno, J. Ichikawa *Saitama Medical University, Japan Background & objectives: Although IgG4 related disease (IgG4- RD) was originally reported in sclerosing pancreatitis associated with increased serum IgG4, IgG4-RD was recognized as systemic disease because of involvement of multiple organs. Soft tissue involvement is rare and diagnostically challenging. Methods: A 60-year-old male noticed a mass in the abdomen one year ago and visited our hospital. The mass was 6 cm and located subcutaneously in the lower abdomen. The mass did not change in size for a year, but surgical resection of the tumour was performed for definitive diagnosis. He had no medical history including auto- immune disease and abdominal surgery. Results: Magnetic resonance imaging study revealed intermediate intensity on T1WI, heterogeneously high to intermediate intensity on T2WI without fat component. Macroscopically, the tumour was well-demarcated, and the inside of tumour was yellow with heter- ogenous myxoid change. Histologically, the mass was fibromyxoid tumour with mild lymphocytic and plasmacytic infiltrate with focal aggregates of lymphocytes. Most of the sparsely infiltrated cells were plasma cells, which were positive for IgG and IgG4, and IgG4/IgG ratio exceeded 80%. No light chain restriction was iden- tified by kappa/lambda stains. The patient is free of recurrence or metastasis after the surgery at least for two years. Conclusion: Because of the rare location of IgG4-RD and absence of systemic symptoms, the diagnosis is challenging clinically and histologically. Especially soft tissue sarcoma and haematological malignancy must be carefully ruled out to reach IgG4-RD. Our case shows a unique clinical presentation and histopathological S340