ECP 2023 Abstracts

S279 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 myeloproliferative disorders. Myelofibrosis (MF) is a recognized com- plication that occurs rarely in ET. We aimed to determine its frequency in ET and PV in a Tunisian population. Methods: All patients diagnosed with PV or ET between March 1999 and March 2023 were recruited from the database of the pathology department of Salah Azaiz Institute. Clinicopathological data were retrieved from pathological reports. MF grading was assessed accord- ing to The European consensus on grading bone marrow fibrosis. Results: We included 211 patients diagnosed with ET (151 cases) and with PV (60 cases). Fifteen patients (7,1%) developed MF: 8 cases post-ET and 7 cases post-PV. The median age of patients that devel- oped MF was 57 years, with a sex ratio of 1,5. Grade 2 and Grade 3 post-ET MF were seen in 4 cases respectively (1,9%). Grade 2 post-PV MF was assessed in 4 cases (1,9%) and Grade 3 post-PV MF in 3 cases (1,4%). Bone marrow hypercellularity was recorded in 7 cases with post-ET MF and in 4 cases with post-PV MF. Conclusion: Bone marrow histopathology is an essential tool in chronic myeloproliferative disorders. The finding of MF must arise the diagnosis of primary myelofibrosis, which is the main differential diagnosis of complicated ET. In these difficult cases, a multidiscipli- nary study is determining in the diagnostic workup. E-PS-11-037 ALK positive large B cell lymphoma: clinicopathological study of 37 cases from a tertiary cancer centre in India U. Sakhadeo*, M. Ranade, S. Epari, L. Nayak, B. Bagal, H. Jain, M. Sengar, C. Dhamne, N. Moulik, G. Narula, S. Banavali, T. Shet *Tata Memorial Centre, Homi Bhabha National Institute, India Background & objectives: Anaplastic lymphoma kinase–positive large B-cell lymphoma (ALK+ LBCL) is rare and shows characteristic plasmablastic/immunoblastic morphology with ALK expression. The objective of this study is to examine the clinicopathologic features of ALK+ LBCL to ensure its accurate diagnosis. Methods: We retrospectively reviewed the electronic medical records and archival material for the clinico-pathological details of 37 cases of ALK+LBCL, diagnosed at our institute between 2012 and 2022. Results: The age range was 11-73 years (mean 34.97 years, median 35 years). Male preponderance was noted with M:F of 3.63:1. Immune sta- tus was available in 27 patients and all were immunocompetent. 50% of the patients showed B symptoms and/or advanced stage disease. Major- ity (62%) of patients had both nodal and extranodal disease. 6.9% had isolated extranodal disease. 89.2% cases showed diffuse pattern while nodular and sinusoidal was noted in rest. Majority showed plasmablas- tic morphology. CD138/MUM1/OCT2/BOB1 were variably positive in all cases, indicating plasmablastic/B cell differentiation. Cytoplasmic granular expression of ALK was present in all cases. CD30 showed focal weak staining in 50% cases. Median survival was 13 months. Conclusion: To the best of our knowledge this is the largest single institu- tion study of ALK+ LBCL, which is a rare, aggressive B-cell lymphoma with characteristic clinical-morphologic-immunophenotypic profile and unfavourable outcome. ALK+ LBCL is an important differential diagnosis of plasmablastic/immunoblastic morphologies, particularly in cases with immunocompetent adults and non expression of mature B cell markers. E-PS-11-038 T-Cell lymphomas in solid organ transplantation: review of this rare entity in a tertiary hospital E.P. Sánchez López*, P. Pérez-Montero, G. Olmedilla Arregui, E. García Fernández *La Paz University Hospital, Spain Background & objectives: Outside the context of inborn errors of immunity (IEI), T-cell lymphomas in the setting of immune deficiency/ dysregulation (IDD) are extremely rare and most often are EBV-negative. Our objective is to review the post-transplant associated T-cell lympho- mas diagnosed in our centre. Methods: We searched cases diagnosed as post-transplant lymphopro- liferative disorder (PTLD) in the last 10 years and reviewed the his- tology, immunohistochemistry slides and molecular studies of T-cell lymphomas. We revised the medical records: gender, type and cause of transplant, age at transplantation, immunosuppressive treatment, time to diagnosis of lymphoma and vital status. Results: We found 41 cases of post-transplant associated lymphoprolif- erative disorders (LPD), of which 5 were T-cell lymphomas (12%), 14 B-cell lymphomas, 9 polymorphic lymphoproliferative disorders and 13 hyperplasias. Among the T-cell lymphomas, 4 cases were peripheral T-cell lymphomas (PTCL), NOS and 1 case anaplastic large cell lym- phoma (ALCL), ALK-negative. Two cases were males and 3 females. Three of the transplants were renal, 1 hepatointestinal and 1 intestinal, which later became multivisceral. The ages at transplant ranged from 1 year to 51, and the time from transplant to diagnosis of lymphoma ranged from 3 months to 34 years. All cases were EBV-negative. Two patients died during follow-up and 3 patients are alive. Conclusion: Our results show that T-cell lymphomas are rare and most of them are EBV-negative in this clinical setting. This data correlates with the previous published literature. Interestingly, we found one rare case of ALCL, ALK-negative. The time to diagnosis of lymphoma was variable, although in cases of renal transplantation it took more than 10 years, suggesting perhaps a longer latency time for the onset of T-cell lymphoma in this context. E-PS-11-039 Expression of CD30 in primary central nervous system lymphoma H. Sartelet*, E. Aboud, L. Taillandier, J. Broseus, P. Feugier *Chru nancy, France Background & objectives: Primary central nervous system lymphoma (PCNSL) is an aggressive lymphoma with poor prognosis. The expres- sion of CD30 is known to be a potential target therapeutic biomarker. The aim of the study is to evaluate CD30 expression in PCNSL. Methods: We present a retrospective and unicentric study of 91 adult patients initially diagnosed and treated between January 2011 and December 2019 at the University Hospital of Nancy for PCNSL. We excluded the patients with systemic relapse or meningeal involvement or with EBV related disease. The antibodies used were against CD79a, CD20, CD10, CD3, CD5, BCL6, MUM1, CD30, and Ki67. Results: Among the 91 patients, the repartition of gender is nearly equal with a low predominance of male (51.6%) and the median age at diagnosis is 67.8 years. The average of follow-up is less than 2 years (22 months). It is observed more non-GC PCNSL than GC subtype (75 vs 16). 14% of PCNSL (13/91) express CD30. Their median survival is 27 months (cd30+) versus 7 months for CD30 negative PCNSL but the difference is not significant. The PCNSL CD30+ are significantly more non-GC lymphoma (12/13, p=0.01) and the expression of CD30 is significantly negatively correlated with those of CD10 and Bcl-6 (p<0.01). Conclusion: The presence of CD30 found in 14% of PCNSL may be useful to enlarge the therapeutic panel proposed to patients after relapse or refractory disease. E-PS-11-040 Not every bearded man is your grandfather. Crystal storing histio- cytosis: a case report and literature review S.N. Sayir*, E.D. Serbes, S. Yüksel, G. Kaygusuz *Ankara University, Faculty of Medicine, Turkey Background & objectives: Crystal storing histiocytosis (CSH) is a rare entity characterized by the accumulation of immunoglobulin crystals (especially kappa light-chains) in the cytoplasm of histiocytes