ECP 2023 Abstracts

S319 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 E-PS-16-002 Cellular variant of focal glomerulosclerosis: a single centre experience M.L. Abascal Camacho*, Y. Gómez Navarro, C. Vieru, M.T. Mora Mora, Ú. Verdalles Guzman, F. Arias, F.J. Díaz Crespo *Hospital General Universitario Gregorio Marañón, Spain Background & objectives: Focal segmental glomeruloesclerosis (FSGS) is a heterogenous entity with 5 histologyc patterns based on columbia FSGS Clasiffication: not otherwise specified (NOS), collaps- ing, tip, perihilar, and cellular variants. The cellular subtype is the lest frequent, accounting for only 3% of cases Methods: We performed a retrospective study of renal biopsies, between 2018-2023, obtaining 5 cases of cellular FSGS. The inclu- sion criteria was the presence of at least one glomerulus with segmental expansion of the glomerular tuft with endocapillary hypercellularity occluding luminas and the exclusion of collapsing and tip variants. Mean age of diagnosis was 64 years with male predominance. Results: Medical history was diverse, 2 cases had hypertension,1 fibrilloid arteropathy and 1 toxic substance abuse. The mean serum creatine was 1,19mg/dl, proteinuria 8,3gr/24h, eGFR 60ml/min and serum albumin 2,34g/dl. Microhematuria was present in 75%. Light microscopy revealed mean 8% sclerosed glomeruli and 25% segmen- tal endocapillary proliferation and sclerosis, and the cellularity was composed of histiocytes in 100% and neutrophils in 75% of cases. The remaining glomeruli showed endocapillary hypercellularity (out of segmental lesions) in 75% of cases with a mean of 50% affected. The interstitium showed minimal lymphocytic infiltration, fibrosis and tubular atrophy. Inmunofluorescence examination was negative. Elec- tron microscopy revealed extensive foot process effacement, without deposit in 100% of cases. Conclusion: Our study, although based on a small number of cases, indicates a higher incidence in adult males with nephrotic syndrome. Microscopy findings highlights the presence of proliferative endocap- illary lesions in glomeruli not affected by segmental sclerosis. Renal biopsy plays a crucial role in accurate diagnosis for early detection and management. Further research is needed in order to understand the underlying pathology mechanisms and develop effective treatment strategies, as some cases progress to kidney failure. E-PS-16-003 Cristal storing light chain histiocytosis: case report M.L. Abascal Camacho*, T. Bada Bosch, M. Fernandez Nieto, F. Arias, Y. Gómez Navarro, F.J. Menarguez Palanca *Hospital General Universitario Gregorio Marañón, Spain Background & objectives: Crystal-storing histiocytosis (CSH) is a rare entity within monoclonal gammapopathies of renal significance (MGUS) characterized by histiocyte infiltration containing light chain crystals. We present a case diagnosed by renal and skin biopsy with CSH. Methods: A 71-year-old woman was diagnosed with IgG-kappa MGUS in 2011. Later, she developed purpuric lesions and acute kidney failure (AKF) with persistent low C4, IgG-K serum and urine mono- clonal component. She was clinically diagnosed of ANCA-negative vasculitis and received immunosuppressive treatment based on Cyclo- phosphamyde and Rituximab. In 2022, she experienced new onset AKF and purpuric lesions. A biopsy was performed. Results: Light microscopy showed global mesangial proliferation along with endocapillary hipercelullarity composed by monocytes and neutrophils. Additionally, it was presented focal and segmental dilation of capillary loops with obstruction by histiocytes (CD68+) containing eosinophilic cytoplasmic inclusions, with angulated appear- ance in some sections. Immunofluorescence showed Kappa positivity restriction (3+) on intracytoplasmic deposits. Electron microscopy revealed capillary lumens occupied by histiocytes with markedly elec- tron-dense inclusions of varying sizes, amorphous and some crystalline with angulated appearance corresponding to intracytoplasmic crystals. Skin biopsy revealed overlapping features in dermal capillaries with presence of fibrin thrombi tactoids (CD61+). Bone marrow biopsy was performed, showing polyclonal plasmacytosis of 15% without histiocytes. Conclusion: HAC is a rare entity, which usually occurs around 60 in men. It is unclear whether crystal formation occurs within plasma cells and is digested by histiocytes or if crystals form in histiocytes due to a failure in light chain degradation. HAC is a systemic disorder affecting multiple organs, being renal involvement typically interstitial rather than glomerular, with a poor vital prognosis, most diagnosed on autop- sies. Treatment targets with bortezomib and autologous hematopoietic cell transplantation achieve remission in some cases. E-PS-16-004 Anti-oxidant and anti-inflammatory effects of montelukast in pre- venting Iohexol-induced contrast-induced nephropathy in rats E. Baris*, O. Simsek, C. Ural, C. Incir, S. Aydemir, M. Gumustekin, Z. Cavdar, O. Yilmaz, S. Ozbal, M.A. Arici *İzmir University of Economics, Faculty of Medicine, Department of Medical Pharmacology; Izmir, Turkey Background & objectives: Pathophysiology of contrast-induced nephropathy (CIN) includes reactive oxygen species (ROS) genera- tion, inflammation and apoptosis. In this study, the prophylactic effect of Montelukast (M) with antioxidant, anti-inflammatory and anti-apop- totic properties was investigated in rats with CIN. Methods: Rats randomized into four groups: 1.Control (C), 2.CIN (iohexol; 3 g iodine/kg), 3.M (10 mg/kg), 4.M+CIN. Rats were sacri- ficed on the 7th day. Kidney injury was evaluated histologically. Serum kidney injury molecule-1 (KIM-1), urea, serum and urine creatinine levels were measured. Tumour Necrosis Factor-α (TNF)-α, Nuclear Factor-κB (NF-κB), KIM-1 mRNA expressions, ROS levels, active caspase-3 were analysed in the kidney. Results: Serum and urine creatinine levels slightly increased in the CIN group compared to the C (p>0.05). Renal tubular damage increased in the CIN group compared to the C (p<0.01). Increased mononu- clear cell infiltration (MNC) in the CIN decreased in M+CIN. TNF- α, NF-κB, KIM-1 mRNA expressions and ROS levels increased in CIN group compared to the C (p<0.001 and p<0.05). TNF-α, NF-κB, KIM-1 mRNA expressions and ROS levels decreased in the M+CIN group compared to the CIN (p<0.001 and p<0.001). Active caspase-3 immunostaining score of CIN increased compared to the C (p<0.01) whereas decreased in the M (p<0.05) group compared to CIN group. Conclusion: Montelukast pretreatment produced antioxidant, anti- inflammatory effects in the CIN group. This study demonstrated mon- telukast pretreatment decreased renal tubular injury and MNC infil- tration in kidneys via downregulating TNF-α, NF-κB, KIM-1 mRNA expressions along with ROS levels. These pre-clinical findings might contribute the pathophysiology of CIN and development of the mon- telukasts’ repurposing strategies for preventing CIN. Funding: This study supported by Dokuz Eylul University (Project number:2019.KB.SAG .068). E-PS-16-005 Predictive value of activity and chronicity indices in lupus nephritis I.D. Căruntu*, T. Azoicai, E.R. Avadanei, M. Onofriescu, A. Covic, S.E. Giu ș că *"Grigore T. Popa" University of Medicine and Pharmacy, Romania Background & objectives: Renal damage in lupus nephritis (LN) consists in different glomerular and interstitial lesions that delineate diagnostic criteria for classification. Our study focuses on the activity