ECP 2023 Abstracts

S273 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Cyclin D1, MUM1, Bcl2, Bcl6, and Ki-67). The expression profile of immunohistochemical markers (CD10, Bcl6, and MUM1) established the cell of origin of this case of DLBCL by using the Hans algorithm. Conclusion: The current report highlights the importance of early diagnosis of CD5-positive DLBCL because of its poor prognosis and calls attention to the critical importance of identifying immunodefi- ciencies because doing so affects the types of treatments available. Although cell-of-origin helps predict outcomes, the germinal centre B cell-like and activated-B cell-like subtypes remain heterogeneous, with better and worse prognostic subsets within each group. E-PS-11-014 Expression of PIM1 and MYD88 in diffuse large B-cell non-Hodg- kin’s lymphomas –10 years of experience and 50 cases M. Cristian*, M. Aschie, A. Mitroi, M. Deacu, A.A. Nicolau, G. Bal- tatescu, N. Dobrin, E. Matei, C.S. Branzan, I. Poinareanu *Center for Research and Development of the Morphological and Genetic Studies of Malignant Pathology - CEDMOG, “Ovidius” Uni- versity of Constanta, Romania; Department of Clinical Pathology, “Sf. Apostol Andrei” Emergency County Hospital, Constanta, Romania Background & objectives: Oncogenically active MYD88 mutations are found in one-third of ABC-DLBCLs and PIM1 has been found in over 50% of DLBCLs. We aimed to determine the level of MYD88 andPIM1 expression, and their associations with clinicopathological parameters in DLBCLs. Methods: This retrospective study included 50 cases of DLBCL diag- nosed at the Pathology Department of the Emergency County Hospital of Constanţa and Sacele County Hospital of Brasov between 2012 and 2021. MYD88 and PIM1 protein expression was evaluated by immu- nohistochemistry (IHC) using two different scoring systems and was assessed by two experienced pathologists with good collaboration. Results: Diffuse large B-cell lymphomas interest both sexes equally (1:1). Non-Hodgkin’s diffuse large B-cell lymphoma, NOS is the most common type of lymphoma in the studied group of patients (80%), with an alignment of the results obtained with the data provided by the WHO 2022. IHC analysis was performed using monoclonal antibodies against MYD88 and PIM1. MYD88 mutation more frequently affects female adults and an increased incidence of PIM1 has been observed in older men. In the cohort analysed in this research, diffuse large B-cell lym- phomas exhibit a high frequency of PIM1 mutation (50%), as shown by the IHC method, compared to the presence of MYD88 mutation (16%). Conclusion: In conclusion, our preliminary data suggests that the immunohistochemical expression of PIM1 and MYD88 in our DLBCL cohort may improve the diagnosis and prognosis of DLBCL patients. The presence of the mutation, together with its protein overexpression, could also be used as a prognostic marker in advanced-stage DLBCLs. Funding: This study was funded by ”Grants competition in bio-medical field 2021”, Contract no. 5/21/10.2021, registered by ”Ovidius” Uni- versity of Constanta with no. 14453/21.10.2021 and supported by the Institute of Doctoral Studies, School of Medicine, ”Ovidius” University of Constanta. E-PS-11-015 A diagnostic challenge: castleman disease - plasma cell variant with monotypic lambda light chain plasmacytic proliferation A. Cutitaru*, D. Ferariu, I.D. Căruntu *"Grigore T. Popa" University of Medicine and Pharmacy of Iasi, Romania Background & objectives: Castleman disease (CD) represents a het- erogeneous group of nonclonal lymphoproliferative disorders includ- ing 4 histological subtypes with clinical diversity. Pathogenic mecha- nisms involve immune dysregulation, IL-6 having a critical role. CD is regarded as an orphan disease, with global incidence still unknown. Methods: We report a case of a 62 year-old male patient, admitted in Oro-Maxillo-Facial Surgery Department – “Sf. Spiridon” Clinical Emergency County Hospital of Iasi to investigate a rapidly progress- ing large mass developed in the left submandibular region. Clinical and imaging exams revealed a multicentric lymph node involvement (submandibular and laterocervical). Subsequently, excision of affected lymph nodes was performed by surgeons. Results: Macroscopically, one sample (6/4/2 cm) presented a nodu- lar structure (3/2.5/2 cm), red-brown on cut section; another sample (2.5/1.6/1.2 cm) included two nodular structures. In both samples, histopa- thology showed three lymph nodes with partially preserved histoarchitec- ture: free subcapsular sinuses; normal or hyperplastic follicles (displaying marked germinal centres surrounded by small lymphocytes, hyalinization and penetrating arterioles – typical for CD); highly vascularized interfol- licular and medullary areas, occupied by mature, monomorphic plasma cell aggregates with large, hyperchromatic nuclei, lacking brisk mitotic activity. Immunohistochemistry revealed: CD20+ and CD3+ in lymphoid follicles, with predominant mantle zone CD3+; CD21+ in follicular den- dritic cells; HHV8-; kappa/lambda chain+ in plasma cells, with lambda chain restriction indicating monotypic proliferation. Conclusion: The pathologic spectrum of CD includes hyaline vascular, plasma cell (PC), mixed, and HHV-8 subtypes. Histology corroborated with immunophenotype supports the final diagnosis of multicentric CD – PC variant with monotypic lambda light chain plasmacytic prolifera- tion. In PC variant, proliferation is typically polyclonal; rarely can be monotypic, predominantly lambda light chain restricted (IgG/ IgA). The case report is valuable considering the presence of monotypic lambda chains, in an HIV-negative patient, without other clinical mani- festations (i.e., POEMS syndrome), with favourable outcome. E-PS-11-016 Intraparenchymal low grade B-cell lymphoma of the CNS: a case series and literature review M.T. Dawid de Vera*, F.J. Díaz de la Pinta, F.J. Díaz-Crespo, M. Conde Ferreirós, D. Morillo Giles, S.M. Rodríguez-Pinilla *Hospital Universitario Virgen de la Victoria, Spain Background & objectives: Low grade B-cell lymphomas of the cen- tral nervous system (CNS) are infrequent entities, most commonly extranodal marginal zone B-cell lymphoma (MZBCL-CNS). We pre- sent a series of cases of intraparenchymal low grade B-cell lymphomas of the CNS and a literature review. Methods: Our series consisted of 2 men and a woman, with a mean age of 65 years. One patient suffered an outbreak of multiple sclerosis 20 years ago. All of them presented with headache and neurological focality. Imaging tests showed a subcortical white matter lesion of the frontal lobe (2 cases) and cerebellum. A biopsy was taken on suspicion of lymphoma. Results: Case 1 shows intraparenchymal aggregates of plasma cells with light chain restriction and few small CD20+ lymphocytes in a perivascular arrangement. Case 2 exhibits an intraparenchymatous infiltrate of small lymphocytes with CD20 and BCL2 expression with- out plasmacytic differentiation. Case 3 shows a diffuse small cleaved nuclei lymphoid infiltrate with occasional large cells expressing CD20, CD10, BCL6 and BCL2. All cases have low-moderate proliferative index with absence of MYD88 gene mutation. The final diagnosis is MZBCL-CNS (cases 1 and 2) and primary cerebellar follicular lym- phoma (FL) (case 3). Systemic involvement was ruled out. Two patients received radiotherapy or chemotherapy and remain stable after diagno- sis. The remaining patient died of other causes. Conclusion: Primary MZBCL of the CNS commonly affects the dura mater, while exclusively intraparenchymatous location has been exceptionally described, with only 11 cases reported so far. Secondary involvement by a systemic process should always be ruled out before making this diagnosis. The mean age at onset is 56 years, with main frontal lobe involvement. Complete remission is achieved in 40% of