ECP 2023 Abstracts

S281 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 (26/28), CD79a(-)(12/22), EBER and/or EBV-LMP1(+)(11/15). 16 patients’ ki-67 levels were 80% and over (range=50-100%). 15 out of 17 patients had no bone marrow infiltration. One of the patients had a previous history of diffuse large B-cell lymphoma, and one patient had a previous history of Burkitt lymphoma. Conclusion: PBL is a rare lymphoma type with a worse prognosis and the main challenge with PBL is considering it as a differential diagno- sis. After evaluating the general status of the patient, it is important to focus on the immune-suppression history of the patient. Then immuno- histochemistry and morphological features help pathologists to give the correct diagnoses. Lastly, plasmablastic lymphoma diagnosis should be kept in mind in HIV(-) immunopotent patients with extraordinary infiltration sites. E-PS-11-044 Angiosarcoma of the liver and spleen with thrombocytopenia and haemolytic anaemia (Kasabach–Merritt Syndrome) A. Therapontos*, N. Stavrinou, E. Athanasiou, E. Spiteri, P. Vla- chou, F. Dolkiras, T. Georgiadi, A. Antonopoulou, G. Kyriakopoulos *Department of Pathology, Evaggelismos General Hospital Athens, Greece Background & objectives: Kasabach–Merritt syndrome is character- ized by thrombocytopenia secondary to the entrapment and platelet consumption by the vascular spaces of a vascular neoplasm (benign or malignant). We describe a case with severe thrombocytopenia and haemolytic anaemia in a patient with liver-spleen angiosarcoma. Methods: A 64-year woman presents with marked swelling of the liver and spleen with thrombocytopenia (100.000 platelets) and anaemia (21 hema- tocrit) in the context of Coombs-negative haemolytic anaemia. The clinical differential diagnosis included haematological disease (lymphoma). Fine needle biopsy with transoesophageal ultrasound was performed. Results: The neoplasm was characterized by large anaplastic nuclei isolated or in aggregates with abundant eosinophilic cytoplasm with presence of sufficient hemosiderin. The extended immunohistochemi- cal analysis was negative for markers of haematological, epithelial, neuroendocrine, melanocytic, histiocytic and hepatocellular differ- entiation while it exhibited strong positivity for vascular differentia- tion markers such as CD31, ERG, Fli-1 και Factor VIII establishing the diagnosis of angiosarcoma with proliferation index ki-67 30%. Thrombocytopenia and Coombs-negative haemolytic anaemia were interpreted within the context of Kasabach–Merritt syndrome. Conclusion: Angiosarcoma of the liver and spleen can cause thrombo- cytopenia due to platelet consumption and Coombs-negative microan- giopathic haemolytic anaemia within the context of Kasabach–Merritt syndrome E-PS-11-045 Amyloid accumulation in bone marrow: clinicopathological fea- tures in systemic amyloidosis C. Utku*, D. Demir, B. Sarsik Kumbaraci, N. Ozsan, F. Keklik Karadag, M. Yetisken, M. Hekimgil, S. Sen *Department of Pathology, Ege University Faculty of Medicine, Izmir, Turkey Background & objectives: Amyloidosis is characterized by amyloid accumulation in various tissues, leading to dysfunction. The aim is to evaluate the amyloid accumulation in BM interstitium, vascular, peri-cortical soft-tissue besides bone-trabeculae and cartilage by semi- quantitatively and determine the possible correlations among clinico- pathological features. Methods: The study analysed 213 BM biopsies performed on 157 patients in our department between 2014-2019. The diagnosis was established with Congo-red under polarized-light by at least two pathologists. Some slides were examined under fluorescence-filter; also, tioflavinT/tioflavinS stains were evaluated with isotiosiyanat-filter. Amyloidosis type, involvement of other organs, plasma cell percentage, clonality, and repeated biopsies according to progression were analysed retrospectively. Results: The male-to-female ratio was 1.24:1, and the mean age was 61.89. Most of the patients had vascular amyloid depositions in BM. The most commonly involved other organs were the kidney, myocar- dium, and gastrointestinal tract, respectively, and five patients had manifestations in multiple sites. AA amyloidosis was observed in 19 patients. Of the patients, 44 presented without myeloma, 60 had simultaneous myeloma, and 14 had a previous myeloma history. In 39 patients, mye- loma developed after amyloidosis within 8.5 months. The most com- monly accompanying diseases were myeloma with lambda and, accord- ing to immunoglobulin (IG) depositions IGG (55.8%), IGA (21.1%), and light-chain (17.9%), respectively. Immunohistochemically, CD56 positivity was identified in 25.3% of myelomas. Conclusion: The prognosis depends on various factors, such as the underlying cause, the extent of amyloid deposition, and other comor- bidities. In this condition, amyloid deposits interfere with the normal functioning of the BM. Amyloid accumulation can be seen in non-AL amyloidosis types on the BM biopsies. It is essential to perform a BM biopsy to diagnose and manage systemic amyloidosis. The biopsy can help determine the type and extent of amyloid deposition in the body, which can guide treatment decisions. E-PS-11-046 Low-grade nodal B cell lymphoma co-expressing CD5 and CD10 but not CD23 or cyclin D1: a case report with diagnostic challenge K. Win*, S. Chuang *Department of Pathology, Chi-Mei Medical Center, Taiwan Background & objectives: Co-expression of CD5 and CD10 is unu- sual in B-cell lymphomas. Either the biologic basic or clinical sig- nificance for such co-expression is unclear. Yet, this rare event may complicate the interpretation of lymphoma immunophenotyping. We present one such challenging case. Methods: A 63 year-old male patient without a significant past history presented to our hospital with palpable neck mass bilaterally. There is no fever or other clinical symptoms. Blood count showed anaemia and leukocytosis with normal platelets and lymphocytosis (abnormal lym- phocyte 33.0%). Neck computed tomography (CT) revealed bilateral cervical, axillary and superior mediastinal lymphadenopathies. Right cervical lymphadenectomy was performed for diagnosis. Results: Flow cytometry showed a distinct B-cell population express- ing lambda immunoglobulin light chain, with CD5+/CD10+/CD19+/ CD20+/CD23-/CD43- phenotypes, raising possibility of mantle cell lymphoma. Histologically, effacement of nodal architecture by diffuse and nodular patterns was seen. The diffuse areas contain small atypical lymphocytes with slightly irregular nuclear contours and pale cyto- plasm. The nodular areas are composed of small and large lymphocytes without polarity. Immunohistochemical study showed the small atypi- cal lymphocytes are B-cells expressing CD5, CD10, CD20, bcl-2, IgM, MNDA, but not CD3, CD23, bcl-6, IgD, SOX11, or cyclin-D1. The Ki-67 labelling index is low. Bone marrow and blood involvements are present. Abdominal CT showed multiple abdominal and pelvic lym- phadenopathies together with a splenomegaly. Conclusion: We present a rare case of a low-grade nodal B cell lym- phoma expressing both CD5 and CD10 but not CD23 or cyclin D-1, and which also manifests splenomegaly, bone marrow and blood involve- ment with the same immunophenotypic profiles. These elements taken together suggest secondary nodal involvement by splenic marginal zone lymphoma (SMZL). Dual expression of CD5 and CD10 is extremely unusual, and can lead to misdiagnosis. Detailed clinical information and a comprehensive immunophenotyping are paramount for the diagnosis.