Case Reports in Nephrology

Several theories have been proposed to explain the development of severe acute kidney injury (AKI) in patients with minimal change nephrotic syndrome (MCNS), but the exact mechanism remains unclear. We encountered an elderly patient with biopsy-proven MCNS who suffered from oliguric AKI, which required hemodialysis at the onset and during the first relapse of nephrotic syndrome. Throughout her relapse, we were able to monitor tubular injury markers, namely, urinary N-acetyl-β-D-glucosaminidase and urinary alpha-1-microglobulin levels. This patient had hypertension. 8.5 years after achieving complete remission, she experienced a relapse of nephrotic syndrome accompanied by AKI, necessitating hemodialysis. The hemodialysis was discontinued after 7 weeks of corticosteroid therapy and cyclosporin A treatment. During this relapse, we observed a correlation between the sudden increase in renal tubular injury markers and proteinuria levels and the progression of severe AKI. Conversely, a reduction in renal tubular injury markers and proteinuria was associated with the resolution of AKI. The abrupt elevation of both tubular injury markers and proteinuria levels suggests a possible breakdown in protein endocytosis in proximal tubular cells. Moreover, it is less likely that the acute reduction in intra-glomerular pressure is the primary cause of tubular injury, as it might result in a decrease in both glomerular filtration rate and proteinuria levels. It is conceivable that massive proteinuria, in conjunction with the patient’s clinical characteristics, may contribute to tubular injury, ultimately leading to severe AKI in this patient.

Thrombotic microangiopathy (TMA) reflects a syndrome of endothelial injury characterised by microangiopathic haemolytic anaemia (nonimmune), thrombocytopenia, and often end-organ dysfunction. TMA disorders are well-recognised in kidney transplant recipients, often due to an underlying genetic predisposition related to complement dysregulation, or de novo due to infection, immunosuppression toxicity, or antibody-mediated rejection. In pregnancy, TMA disorders are most commonly due to severe pre-eclampsia or HELLP, but may also be due to thrombotic thrombocytopenic purpura (TTP) or complement-mediated (atypical) haemolytic uremic syndrome (aHUS). Complement dysregulation is being recognised as playing a role in the development of preeclampsia and HELLP syndrome in addition to aHUS. Due to overlapping clinical and laboratory features, diagnosis can be difficult and delays in treatment can be life-threatening for both mother and fetus. This report describes a 32 year-old female who had two successive wanted pregnancies. The first pregnancy was terminated at 22 weeks gestation due to presumed severe preeclampsia and fetal growth restriction in the context of known chronic kidney failure due to reflux nephropathy. A living-related kidney transplant was performed to improve the chances of pregnancy resulting in a live birth. A subsequent pregnancy was complicated by progressive kidney impairment and hypertension at 22 weeks gestation. Kidney biopsy showed TMA, but the etiology was unclear. This report highlights the diagnostic dilemma of TMA in a pregnant kidney transplant recipient and a role for the anti-C5 terminal complement blockade monoclonal antibody eculizumab, in pregnancy-associated TMA, especially at a peri-viable gestation.

Background. The syndrome of tubulointerstitial nephritis and uveitis (TINU) is a rare oculorenal condition, mainly seen in children and women. The underlying cause of this disease is unknown. Case Presentation. We report a 24-year-old male without any past medical history, diagnosed with bilateral uveitis and azotemia. Biopsy revealed tubulointerstitial nephritis, consistent with TINU syndrome. Fluorescein angiogram revealed peripheral retinal vasculitis. Discussion. TINU is a rare disorder that needs to be distinguished from sarcoidosis, Sjogren’s disease, and tuberculosis. Treatment is indicated in patients with progressive renal insufficiency, consisting of steroid therapy. Most patients recover kidney function. Its early recognition is important to offer the best chance of organ preservation.

Introduction. Longer survival in dialysis led to a higher incidence of vascular access complications and failure. With the limited access to kidney transplantation programs and peritoneal dialysis, exhaustion of vascular access for hemodialysis is an increasingly common situation. Among the available options, atrial tunneled dialysis catheter (ATDC) has been reported as an effective vascular access in this population. Methodology. We report the experiences of two nephrology centers in Tunis with ATDC as an ultimate vascular access for dialysis. Case Reports. Two patients with exhausted vasculature underwent ATDC insertion in 2020 and 2022, respectively, as a vascular access of last resort. Both patients underwent CRBI, which resolved with favorable outcomes. One case was complicated by post-operative thrombosis and was successfully treated with thrombolysis. Both patients are currently on dialysis via their ATDC with a catheter patency of 29 months. Conclusion. ATDC is a life-saving and safe vascular access in cases of depleted vasculature. Little more than 50 cases have been reported in the literature during the last 30 years. As the frequency of vasculature exhaustion is expected to increase, preservation of veinous access in patients at risk of chronic kidney disease have never been more crucial.

Acute kidney injury (AKI) poses a substantial challenge in the management of lymphoma patients and is frequently associated with diverse causative factors. Herein, we report an illustrative case involving a 47-year-old male with influenza A infection who developed severe AKI, which was incongruent with his medical history. Laboratory investigations disclosed aberrant immunoglobulin levels and urinary protein excretion, prompting further evaluation. A renal biopsy revealed the presence of infiltrating lymphoid cells and cast nephropathy, raising suspicion of an underlying hematological disorder. A comprehensive diagnostic workup, including positron emission tomography imaging and bone marrow biopsy, culminated in the definitive diagnosis of splenic marginal zone lymphoma. This case highlights the crucial significance of including lymphoma-associated kidney disorders in the evaluation of unexplained AKI, particularly when encountering unconventional clinical and laboratory results. Swift and precise intervention is of utmost importance in attaining positive results in these rare and complex clinical situations. This study underscores the persistent concern of AKI in lymphoma patients, with lymphocytic infiltration and cast nephropathy as notable elements contributing to the intricate nature of this condition.

Congenital nephrotic syndrome is an autosomal recessive inherited disorder that manifests as steroid-resistant massive proteinuria in the first three months of life. Defects in the glomerular filtration mechanism are the primary etiology. We present a child who developed severe nephrotic syndrome at two weeks of age and eventually required a bilateral nephrectomy. Genetic testing revealed compound heterozygous variants in NPHS1 including a known pathogenic variant and a missense variant of uncertain significance. Light microscopy revealed crescent formation—an atypical finding in congenital nephrotic syndrome caused by nephrin variants—in addition to focal segmental and global glomerulosclerosis. Electron microscopy showed diffuse podocyte foot process effacement. Confocal and Airyscan immunofluorescence microcopy showed aggregation of nephrin in the podocyte cell body that is not a result of diffuse podocyte foot process effacement as seen in minimal change disease. These findings confirm the novel variant as pathogenic.