Case Reports in Nephrology

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.

Background. Urinary lithiasis constitutes a recurrent pathology affecting a relatively young population. The risk of progression to chronic renal failure and the cost of treatment are the most important issues. Primary hyperparathyroidism (PHPT) is responsible for urolithiasis and nephrocalcinosis in 7% of patients, and it represents the 7th cause of urolithiasis in Tunisia. Unfortunately, it remains an underdiagnosed pathology although it is curable. We aim to determine the clinical, biological, therapeutic, and evolutionary particularities of urinary lithiasis associated with PHPT in a nephrology setting. Methods. This is a monocentric, retrospective, descriptive study which took place in our nephrology department during the period from January 2010 to January 2023. Ten patients were included. All of them underwent blood and urine tests and a morphoconstitutional study of the urinary stones if possible. Results. The median age at diagnosis of PHPT was 42 years (34–54). The median time from the onset of kidney stones to the diagnosis of PHPT was 6.2 years (1–17). The male/female gender ratio was 0.66. Five patients had hypertension, two patients had obesity, one patient had diabetes, and three patients had urinary tract infections. Kidney stones were bilateral in eight cases and unilateral in two cases. Nine patients underwent urological intervention: surgery in 5 cases associated with nephrectomy in one case, extracorporeal lithotripsy in 4 cases, and percutaneous nephrolithotomy in two cases. The diagnosis of PHPT was retained with high or uncontrolled PTH associated with hypercalcemia in 8 cases and normocalcemic PHPT was found in 2 patients. Two patients had parathyroid adenoma and one patient had mediastinal adenoma. Radiology exploration was normal for the others patients. Surgery was performed in 7 patients and histology revealed an adenoma in 5 cases and hyperplasia in one case. The predominant urinary risk factors in our study were hypercalciuria in 6 cases and insufficient diuresis in 4 cases. Conclusion. This study underlines the role of the nephrologist in the exploration of urinary lithiasis and the prevention of recurrences, especially as PHPT is a curable aetiology of urolithiasis and affects a relatively young population. The determination of the epidemiological profile of patients with stones associated with primary PHPT and lithogenic risk factors allows the primary and secondary prevention of stone formation.

Myoglobin cast nephropathy occurs in cases of acute renal injury in which large amounts of myoglobin accumulate in the renal tubules, presenting as muscle pain, reddish-brown urine, and elevated creatine kinase levels. Our case describes a 60-year-old male who came to the emergency department with fevers, mild abdominal pain, and constitutional symptoms one day after returning to the United States from a trip to Nigeria. Initial workup demonstrated an acute kidney injury and elevated aminotransferase levels and the patient was started onatovaquone-proguanil for possible malaria given a recent diagnosis in Nigeria. Two days later, the patient was found to have rhabdomyolysis, resulting in a renal biopsy that showed myoglobin cast nephropathy. Previous literature has suggested mechanisms for the development of rhabdomyolysis in malarial infection, including inflammatory processes, direct effect of parasite accumulation, and drug-induced toxicity. Our case further implicates antimalarial therapy as a cause of rhabdomyolysis and increases awareness of myoglobin cast nephropathy as a potential complication of malaria.