ECP 2023 Abstracts

S320 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 and chronicity indices in LN as valuable tools for assessing aggressive- ness and predicting disease course. Methods: The study group comprised 53 renal biopsies diagnosed as LN by light and immunofluorescence microscopy. The distribution in LN classes and the assessment of activity index (AI) and chronicity index (CI) were performed using the revised ISN/RPS classification including the modified NIH semiquantitative scoring system. Main clinico-biological characteristics were extracted from the patient records. Data were statistically analysed. Results: Histologically, LN cases were classified as class II - 2 cases, class III - 4 cases, class IV - 19 cases, class V - 22 cases, class VI - 6 cases. We registered a noticeable increase of active status from classes II-III to class IV, followed by a small increase in class V and a strong decrease in class VI, and a significant increase in chronic status from classes II-V to class VI. Analysis of ROC and AUC for AI and CI pre- dictive value in relation to clinico-biological parameters showed a good prediction for a GFR <30 ml/min on patient’s appointment, provided by CI (AUC 0.763, p = 0.008). Conclusion: The modified NIH semiquantitative scoring system for AI and CI allows, through new cut-offs for the glomerular and tubulointer- stitial lesion – assigned scores of 0 to 3, an accurate evaluation of sever- ity degree. In our study, AI and CI showed great variability between diagnostic classes and within the same class. Our work added valuable results in the evaluation of active and chronic indices in LN – that still require further refinement to improve interobserver reproducibility and to validate prognostic value. E-PS-16-006 Congenital nephrotic syndrome: a case series A. Demir*, K. Erdogan, G. Gonlusen, B. Atmış, A. Karabay Bayazıt *Çukurova University, Pathology Department, Turkey Background & objectives: Congenital nephrotic syndrome (CNS) is characterized by massive proteinuria, hypoalbuminemia and oedema. We present a case series of CNS. Methods: Five CNS cases were enrolled into this study. The patients’ clinical datas were collected from medical records. Renal biopsies were evaluated with routine examination, immunoflourescent and electron microscopy. Results: First case was 20-day male that’s renal biopsy was composed of 1/20 cresent formation and mesengial cellularity without immune deposits. Diffuse enhancement of foot process of podocyte and micro- villi formation were found ultrastructurally. Second case was 3 month female. Renal biopsy showed diffuse mesengial cellularity and inter- stitial inflammation without immune deposits. Third case was 22 day male presenting with polyhydramnios and a history of in utero ex sib- ling. Renal biopsy was composed of mesengial cellularity, microcystic areas and inflammatory cells. Fourth case was 1 month male presenting with proteinuria. His renal biopsy was consistent with minimal lesion disease ultrastructurally. Fifth case was a 6 month old male that’s renal biopsy revealed diffuse mesengial sclerosis. Conclusion: CNS has a risk to develop end stage kidney disease. Albeit this progression, CNS patients under dialysis have good out- comes rather other kidney diseases in the infancy. E-PS-16-007 Clinicopathological significance of monotypic light-chain deposi- tion in IgA nephropathy C.A. Gomez Gonzalez*, B. Sarsik Kumbaraci, B. Yaman, D. Demir, Z. Akcali, G. Asci, S. Sen *Department of Pathology, Ege University Faculty of Medicine, Turkey Background & objectives: IgA nephropathy (IgAN) is characterized by the deposition of IgA within the mesangium and can also have light- chain deposition kappa/ lambda in a polytypic or monotypic (mIgAN) profile, with or without bone marrow alterations, conferring different scenarios of clinical outcomes. Methods: Between 2017-2021 retrospectively, renal biopsies with fresh tissue for immunofluorescence assessment were evaluated, and 164 cases with IgA deposition were included. For each case, light- chain and IgA staining were evaluated, and divided into five groups: lambda monotype, lambda predominant, polytype, kappa monotype, and kappa predominant. Histopathologic findings according to Oxford classification were described. In mIgAN cases, bone marrow biopsies were also evaluated. Results: In our series 65% were male, the mean age was 44 ±14 years old, and the follow-up time was 38±21 months. The prevalence of mIgAN and pIgAN was 49%(lambda/kappa=72/8) and 43%(n=70) respectively. In two cases lambda predominance was detected. At the histopathological findings, in mIgAN, endocapillary proliferation was statistically significant(p=0,02). Within mIgAN cases, two cases had diagnoses of myeloma. In the first case, the initial kidney biopsy had weak IgA deposition, and two years later in a bone marrow biopsy myeloma was detected. Seven years follow-up in kidney biopsy “kappa mIgA” deposition was detected. In the second case three years after the bone marrow biopsy, in the kidney biopsy “lambda mIgA” deposition was detected. Conclusion: At the evaluation of IgA deposition, the light-chain co- deposition might correspond to a different entity within IgAN, noticing that mIgAN had an association with hematologic malignancies. There- fore, adequate approach and classification are mandatory for optimal treatment and surveillance of the patients. E-PS-16-008 Significance of C4d and Jones stain in renal amyloidosis C.A. Gomez Gonzalez*, A. Celtik, M. Yetisken, B. Sarsik Kumbaraci, H. Toz, S. Sen *Department of Pathology, Ege University Faculty of Medicine, Turkey Background & objectives: Amyloidosis refers to the abnormal depo- sition of fibrillary proteins within the tissues leading to organ failure. Kidney compromise is usually seen in systemic amyloidosis, grouped into AA, AL, and non-AA-non-AL type amyloidosis. Congo red stain is the gold standard, silver-Jones stain can be positive. Methods: Kidney biopsies performed between 2014 and 2022 at Ege University’s hospital were retrospectively evaluated. Cases with diag- nosis of systemic amyloidosis were included, and grouped into AA, AL and non-AA-non-AL types. For each case distribution of amyloid deposition at hematoxylin-eosin was recorded and compared with histochemistry techniques (congo red and methenamine silver Jones staining) and immunohistochemistry (C4d). Results: A total of 196 kidney biopsies with a diagnosis of systemic amyloidosis were evaluated. AA, AL, and non-AA-non-AL type cases were 122, 47, and 27 respectively. We observed amyloid deposition within the glomeruli, mesangium, basement membrane, and vascular structures. Positive silver staining among amyloid deposits for each group was 24,54% (AA), 76,92% (AL), and 57,89% (non-AA-non-AL). Amyloid deposits in all the groups, in cases where C4d staining was available, had positive results. Conclusion: Congo red staining with evaluation under polarized light is the gold standard for the diagnosis of amyloidosis. In kidney biopsies congo red staining can be faint and hard to be evaluated. Silver staining usually highlights alterations on glomerular base- ment membrane,being negative for amyloid. We detected positive silver staining as well as positive C4d staining among amyloid deposition within the glomeruli, mesangium and basal membranes setting a challenge for differential diagnosis with membranous glo- merulonephritis and fibrillary glomerulonephritis when congo red is unavailable.