ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Background & objectives: Kikuchi-Fujimoto disease is a rare, self- limited disease, characterised by a regional (usually cervical) lymphad- enopathy associated with mild systemic symptoms. The diagnosis relies on histopathological examination which reveals necrotising, histiocytic lymphadenitis with a characteristic absence of neutrophils. The aetiol- ogy remains unknown. Methods: We report the case of a 27-year old male who presented to his general practitioner with mild fever, fatigue, coughing and cervical lymphadenopathy. The diagnosis of COVID-19 infection was established based on PCR testing. Following treatment, the complete resolution of symptoms was noted, except for a persistent cervical lymphadenopathy. Excisional biopsy and histopathological examination of the lymph node was performed Results: The microscopic examination revealed the presence of several irregular areas of necrosis comprised of nuclear debris and apoptotic cells surrounded by an abundant population of histio- cytes. Rare plasma cells were identified in the background of the lymph node, along with normal lymphocytes and some immuno- blasts. A complete absence of neutrophils was also documented. Atypical cells were not identified. Serology and special stains ruled out infectious causes. Immunohistochemical stainings revealed a CD68 positive population of histiocytes and an abundance of CD8 and CD4 positive T cells. Fewer CD20 positive B cells were noted in the background. Thus, a diagnosis of Kikuchi-Fujimoto disease (KFD) was established. Conclusion: Kikuchi-Fujimoto disease is a challenging diagnosis, especially considering that at certain stages of the disease, it can mimic other entities, such as systemic lupus erythematosus or lymphoma. Thus, awareness of this disease is crucial in preventing misdiagnosis and improper treatment. Although its aetiology remains unknown, it is theorised that it may represent a T-cell and histiocyte mediated response to some infectious agents and there are cases reported in the literature of KFD in conjunction with COVID-19 infection or vaccination. E-PS-10-020 Anaplastic large cell mymphoma ALK-negative - MSC(E116K) mutation and novel in-frame fusion-gene EIF4E3-FOXP1 A. Szumera-Ciećkiewicz*, A. Dansonka-Mieszkowska, K. Kurek, O. Kuczkiewicz-Siemion, J. Krzanowski, E. Paszkiewicz-Kozik, G. Rymkiewicz, A. Tysarowski, D. Jesionek-Kupnicka *Narodowy Instytut Onkologii im. M. Sklodowskiej-Curie, Poland Background & objectives: In a subgroup of ALK-negative (ALK-) anaplastic large cell lymphoma (ALCL) a repetitive mutation in the musculin gene [MSC(E116K)] has been recently described. Recur- rent fusion-gene including EIF4E3-FOXP1 has been identified only in single studies under multiple myeloma and breast cancer. Methods: A 62-year-old female with ALK- ALCL, AnnArbor IIIB, IPI-2/5 was qualified for histopathological consultation. Immunohistochemical assessment and the extended molecular testing with a comprehensive 125-gene panel assay dedicated to lymphomas were performed The status of the MSC gene was explored with the Sanger method. Results: The showed classic histopathological ALK- ALCL morphology and immunophenotype (CD30+, ALK-, CD43+/ CD4+/CD3+, Granzyme B+/Perforin+, MUM1+, PAX5-/CD20-, CD15-). Molecularly it was a triple-negative ALK- ALCL with MSC(E116K) mutation and a novel in-frame fusion of EIF4E3 exon 7 to FOXP1 exon 3. Other point changes detected in transcripts included: CDKN2A : c.*29G>C, CREB3L2 : c.299_301del, p. (Thr100del), NOTCH1 : c.5168-1_5168insA, p.(Ser1723LysfsTer2), BATF3 : c.134dup, p. (Asn45LysfsTer17). Our patient had received induction treatment (6 cycles of CHOP) and achieved complete remission (CR). The consolidation treatment included high-dose chemotherapy with Be-EAM supported by auto SCT. After two years of follow-up, the patient presents with CR, with no symptoms suggesting disease progression. Conclusion: ALK- ALCL shows a variable and potentially "molecularly-related" prognosis. We present for the first time the coexistence of MSC(E116K) and EIF4E3-FOXP1 fusion-gene. The importance of these genetic changes is still limited. MSC(E116K) mutation seems to be related to DUSP22 rearrangements and a better prognosis. The EIF4E3-FOXP1 fusion-gene was not previously described in ALCL; therefore it’s crucial to study ALCL in-depth on larger groups of patients concerning clinical prognosis. E-PS-10-021 Littoral cell angioma of the spleen: unexpected finding in sple- nectomy specimen. Case report and review of the literature G.G. Yange Zambrano*, G. Moreno-De-Juan, Y. Carreres-Ortega, G. Coronado-Vilca, E. Prados-Perez, J.C. Yange-Zambrano, R.F. Ramos-Asensio *Hospital Mateu Orfila, Spain Background & objectives: Littoral cell angioma (LCA) is a rare and benign primary vascular neoplasm of the spleen, with characteristic histopathologic features, reported by Falk et al in 1991. It is thought to arise from the cells lining the red pulp sinuses (littoral-cells). Methods: A 67-year-old man with palpable and hard splenomeg- aly, of 10cm below the costal rim; with leukocytosis, anaemia and plateletopenia. CT-scan showed enlarged spleen (20cm), hetero- geneous, with hypodense nodules inside, some solid and others cystic necrotic; no hyper-enhancement on PET-scan. The differen- tial diagnosis included metastatic disease, lymphoma/leukaemia. Bone marrow biopsy was performed, showing reactive hyperplasia, without neoplastic infiltration. Splenectomy was performed. Results: The spleen weighed 1802gr and measured 24×18.4×6cm. Externally polylobulated-appearance. Serial-sections showed mul- tiple spongy, reddish-venous nodules of variable size, up to 1.5cm, blood-filled, throughout entire spleen. Histologically, the lesions were not-encapsulated, consisted of vascular-channels with red- blood-cells inside. The vascular-lumina showed irregular lining endothelium with both histiocytic and endothelial features, without atypia or mitosis; cells of histiocytic-habitus often sloughed into the lumen and some showed erythrophagocytosis. Papillary-pro- jections into vascular spaces and extramedullary-haematopoiesis were observed. The unaffected white-pulp showed mild reactive follicular-hyperplasia. By immunohistochemistry the tall-lining- cells (with histiocytic-features) were positive for CD68, Factor- VIII, CD163; and the flat-lining-cells (with endothelial-features) were positive for CD31, Factor-VIII. CD8, WT1 were negative. The final diagnosis was LCA. Conclusion: LCA is a rare primary splenic vascular tumour, likely secondary to hemodynamic disturbance in spleen. So far, about 329 cases have been described in the literature. When diagnosed, it is necessary to search for synchronous or metachronous visceral neoplasia. LCA can also mimic metastatic lesion of the spleen. This case report underlines the rarity of this neoplasm, with mor- phological and immunophenotypic features like those described in the literature; that needs to be included in the differential diagnosis of multiple hypodense-splenic-nodules. E-PS-10-022 Kikuchi-Fujimoto disease following vaccination against COVID-19: case report and review of the literature S277