ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 patients included preceded lymphocytic meningitis and daily use of cannabinoids, which have been reported as triggering factors for TINU syndrome. E-PS-16-010 Tubulointerstitial nephritis and eosinophilia in renal biopsy. Prognostic marker? F. Leiva-Cepas*, C. Muñoz Martínez, M.J. Gálvez Medina, I. Sánchez Ramírez, R. Ortega Salas *University Hospital "Reina Sofía", Spain Background & objectives: To determine whether the presence of eosinophils in renal biopsy and haematuria is associated with a worse renal prognosis in patients with tubulointerstitial nephritis (TIN). Methods: Retrospective observational study in 79 (41 were women) patients diagnosed with TIN by renal biopsy between 2000-2020. The patients were classified: presence/absence of eosinophils in the renal biopsy and haematuria in the urinary sedi- ment. Clinical-analytical and histopathological variables were ana- lysed, as well as an analysis of renal survival (GFR<60 ml/min/ m2) in the study follow-up (36.5 months). Results: Antibiotics was the most frequent cause (34.2%). At the time of biopsy, 58.2% of patients had haematuria and 37.7% of patients showed eosinophils on biopsy and had a more severe acute renal failure (ARF). The combination of the groups of esoinophilia in the biopsy and haematuria revealed: 72.4% of the patients with eosinophils in the biopsy presented haematuria, and higher Cr elevation (4.12±2.1 vs 2.96±1.49, p=0.016), proteinuria [21.58 (6.8-86.6) vs 0.12(0.01-2.77) g/24h, p=0.001]. On the other hand, 45.7% of patients in the haematuria group had eosinophils in the biopsy. 45.7% of patients in the haematuria group had eosinophils in the biopsy and 13% had peripheral eosinophilia. Conclusion: Patients with NTI who present eosinophilia in the biopsy and haematuria present a more severe renal failure. The analysis of these parameters could be useful when predicting complications in these patients. Eosinophilia has traditionally been considered a factor that is invariably present in renal biopsies and in peripheral blood, a fact that is not confirmed in our study. E-PS-16-011 The usefulness of IgG4 immunohistochemical staining in differentiation of idiopathic and secondary membranous nephropathy M. Životić*, M. Tubić, I. Filipović, G. Nikolić, S. Radojević Škodrić, D. Dunđerović, J. Filipović, J. Marković Lipkovski *Institute of Pathology, Faculty of Medicine, University of Bel- grade, Serbia Background & objectives: No reliable biomarker has yet been identi- fied that could be used in the differential diagnosis of idiopathic and secondary forms of membranous nephropathy (MN), but it has been shown that IgG4 is the dominant IgG subclass in idiopathic MN. Methods: Here we performed IgG4 immunohistochemical stain- ing (IGHG4/1345, Abcam, 1: 100), on 50 kidney biopsy paraf- fin sections (18 idiopathic and 32 secondary MN). All cases with fine-granular IgG4 deposits along the glomerular basement mem- brane were pointed out as positive. Sensitivity and specificity were calculated. Results: The IgG4 was expressed in glomeruli in 16/18 idiopathic MN (89%), and in 7/32 secondary MN (22%). Overall, the sensitiv- ity of IgG4 for the diagnosis of idiopathic MN was 88.9%, while the specificity was 78.1%. Among secondary MN with positive IgG4, patients had known haematological/immunological disor- ders (plasma cell dyscrasias or IgG4- related disease). The absence of IgG4 was related to all other known secondary causes of MN (systemic lupus erythematosus or malignant non-haematological diseases). Conclusion: IgG was not absolutely specific for the diagnosis of idiopathic membrane nephropathy, but the spectrum of secondary etiological factors leading to a positive finding is clearly narrowed (plasma cell dyscrasias or IgG4- related disease). Nevertheless, IgG4 negative idiopathic MN is not frequently observed, but the negative IgG4 finding in patients without any evidence of second- ary cause at the time of diagnosis, should not sharply exclude pos- sible upcoming secondary aetiology. Funding: Ministry of Education, Science and Technological Devel- opment of Republic of Serbia (No OI 175047) E-PS-17 | E-Posters Neuropathology E-PS-17-001 Novel CLPTM1L-TERT fusion in an IDH-wt WHO Grade 4 left frontal glioma radiologically masquerading as a pilocytic astrocytoma S.H. Lai*, P.Y. Tang, X.F. Chen, B.W.Q. Loke *Singapore General Hospital, Duke-NUS Medical School, Singapore Background & objectives: A previously well 24-year-old man pre- sented with altered mental status. Magnetic resonance imaging revealed a FLAIR mildly hyperintense well circumscribed intra-axial cystic lesion with a T1w isointense solid component showing possible haem- orrhage. Radiological impression was pilocytic astrocytoma. Methods: The resected lesion was examined histologically and extensively interrogated with immunohistochemistry which included GFAP, IDH1, ATRX, p53, Ki67, EMA, CD34, NeuN, neurofilament, SOX10, BRAF V600E, L1CAM, P65 and H3G34R. Further molecular studies included FISH analysis for 1p/19q co-deletion, IDH sequencing, MGMT MS-PCR for promoter methylation and Archer Fusionplex sequencing. Results: The highly vascularised glial neoplasm showed variable morphology of ependymomatous differentiation, pilomyxoid astro- cytoma and oligodendroglioma. Rosenthal fibres and eosinophilic granular bodies were not seen. High grade features such as mitoses, necrosis and microvascular proliferation were noted. The lesion showed GFAP positivity, IDH1-wildtype, conserved ATRX, weak p53 staining and rare EMA perinuclear dot-positivity. Ki67 label- ling was 30%. There were no features of a neuronal differentiation. Patchy BRAF V600E and L1CAM staining was noted but P65 and H3G34R staining were negative. The lesion was 1p/19q intact, negative for mutations in IDH1 and IDH2, and MGMT promoter non-methylated. Archer Fusionplex revealed gene fusion between exon 16 of CLPTM1L and exon 2 of TERT. Conclusion: This was an intriguing glial neoplasm in a young patient, harbouring a unique gene fusion. Single nucleotide pol- ymorphisms at the CLPTM1L-TERT 5p15.33 locus have been described as risk factors for malignancies of the lung, breast and pancreaw. Here, we describe a novel fusion between these 2 genes in a malignant glioma. E-PS-17-002 Pleomorphic xanthoastrocytoma BRAF wildtype, grade 3 – an unique entity in a young patient S313