Clinical nephrology. Case studies最新文献

Karyomegalic interstitial nephritis (KIN) is a rare hereditary form of chronic interstitial nephritis that was first described over 50 years ago. It is characterized by karyomegalic tubular epithelial cells and progressive chronic kidney disease, often leading to end-stage renal disease by the fifth decade of life. Recent studies have identified FAN1 mutations as a key genetic contributor, with additional associations to environmental factors and toxic exposures, such as ochratoxin A, alkylating agents, and heavy metals, which may act as potential triggers of the disease. We present a detailed analysis of KIN cases, highlighting genetic diversity, clinical manifestations, and management challenges, complemented by a comprehensive review of the literature.

Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal disorder with extremely variable presentation. The disease spectrum ranges from completely asymptomatic to 2,8-dihydroxyadenine (DHA) stones to massive deposition of DHA crystals leading to DHA crystalline nephropathy. We report a case of a 45-year-old woman who presented with acute kidney injury and recurrent vomiting. Kidney biopsy revealed precipitation of brown crystals in tubular lumina with acute tubular injury with characteristic birefringence on polarizing light, confirming the unexpected diagnosis of DHA crystalline nephropathy. She was started on a xanthine oxidase inhibitor which resulted in an improvement of kidney function. This case highlights the fact that APRT deficiency can have varied presentations and is an important hereditary cause of crystalline nephropathy.

Introduction: Thrombotic microangiopathy (TMA) is a pathological description which clinically presents with thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and organ dysfunction. The etiology of TMA is broadly classified into four categories: primary hereditary, primary acquired, secondary, and infection associated. H1N1 influenza is a rare etiology of complement-mediated TMA (CM-TMA) with there being under 30 cases reported to date, and its odd presentation with hemoptysis making it a challenge to diagnose.

Case presentation: We present a case of a Caucasian female in her 20s presenting to the hospital with a viral prodrome in setting of a new acute kidney injury (creatinine 8.2 mg/dL), thrombocytopenia (platelet count 14,000/mm³), and H1N1 influenza positive. She developed hemoptysis the next day, with no respiratory distress. Rheumatology work-up for antineutrophilic cytoplasmic antibodies (ANCA), anti-glomerular basement membrane (anti-GBM), and antiphospholipid syndrome (APS) antibodies was negative. CT chest was also negative for pulmonary hemorrhage. Plasma exchange was started empirically until ADAMTS13 activity returned normal (120%), and she was further commenced on eculizumab after an atypical hemolytic uremic syndrome (aHUS)/TMA/Complement 3 Glomerulopathy (C3G) gene panel was sent. Molecular studies revealed a splice site variant of MCP/CD46 gene, which was reiterated on a renal biopsy. The patient was counselled on the genetic results, including predisposition to future events and the importance of long-term eculizumab treatment.

Discussion: CM-TMA is a consequence of alternative pathway dysregulation, commonly associated with genetic mutations which could phenotypically be unmasked by infections, such as influenza virus.

Conclusion: Our case highlights the importance of keeping a broad differential beyond classic pulmonary-renal syndromes in patients presenting with hemoptysis and TMA, while understanding the pathophysiology of infections unmasking genetic mutations in CM-TMA.
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Renal oxalosis occurs from supersaturation of the urine with oxalate in the presence of calcium, resulting in deposition of calcium oxalate crystals within renal tissue and, consequently, progressive renal disease. One of the causes of secondary hyperoxaluria is a high intake of vitamin C, which exceeds the renal excretion capacity, and can induce renal oxalosis. We present a case involving a 67-year-old patient with chronic kidney disease and proteinuria, associated with secondary hyperoxaluria and renal oxalosis, who reported prolonged, excessive intake of vitamin C supplements. The patient presented with a gradual worsening of his renal function and proteinuria during the last 6-month period, after an episode of SARS-CoV-2 infection. The kidney biopsy revealed calcium oxalate crystals within the renal tissue. Thorough investigation and history-taking revealed a substantial increase in vitamin C supplementation during the SARS-CoV-2 infection (up to 3 g daily), indicating secondary hyperoxaluria as the causative factor. Overall during the pandemic, supplement consumption dramatically increased and patients were not adequately informed about the risks of various over-the-counter products. Excessive intake of vitamin C, popularized for its supposed health benefits, can lead, among others, to secondary hyperoxaluria and renal oxalosis. Prompt recognition is pivotal to initiate management and to prevent irreversible kidney damage.

Thromboembolic events are among the most serious, yet rare complications of nephrotic syndrome. While peripheral venous thrombosis and pulmonary embolism are the most common, superior mesenteric artery thrombosis is a rare but life-threatening occurrence. We present a case of severe cytomegalovirus (CMV) infection complicated by congenital nephrotic syndrome, leading to mesenteric ischemia.

A woman with metabolic dysfunction-associated steatohepatitis (MASH) cirrhosis presented to our hospital with hepatic encephalopathy, acute kidney injury, and painful skin lesions. A skin biopsy and broad work-up led to a diagnosis of non-uremic calciphylaxis. Despite treatment with IV sodium thiosulfate therapy, the patient ultimately passed away from infectious complications. This case highlights the need to recognize non-uremic calciphylaxis, which is a dermatologic complication associated with both alcohol-associated and MASH cirrhosis. While treatment options are currently limited, recognition of non-uremic calciphylaxis is crucial for enabling honest conversations with patients about prognosis.

Minimal change disease (MCD) accounts for 10 - 15% of idiopathic nephrotic syndromes in adults. Chronic hepatitis C virus (HCV) infection is rarely ascribed as a cause of MCD and was previously associated with interferon-based therapy. MCD in treatment-naïve chronic HCV infection is extremely rare, with only 3 cases reported in the literature. We report on a 67-year-old woman presenting with acute nephrotic syndrome and severe acute kidney injury requiring short-term dialysis. She was initially treated empirically with glucocorticoids and underwent a kidney biopsy that revealed MCD with evidence of acute tubular necrosis and mild focal acute interstitial nephritis. An extensive work-up was only significant for the presence of anti-HCV antibody with an elevated HCV viral load of genotype 1b. Her kidney function recovered, and she was discharged on an oral prednisone course with a planned taper. 4.5 months later, her HCV infection was treated with ledipasvir and sofosbuvir, and she achieved sustained virological response. The nephrotic syndrome remained in remission 24 months after initial presentation. This is a unique case where sustained remission of both the nephrotic syndrome and the HCV infection were achieved with glucocorticoids and direct antiviral agents, respectively.

A 47-year-old woman with a 12-year history of anemia and high C-reactive protein (CRP) levels was admitted to our hospital with worsening fatigue and night sweats. She had high levels of immunoglobulin G (IgG; 4182 mg/dL), IgA (630.6 mg/dL), and CRP (7.44 mg/dL); a low hemoglobin level (8.9 g/dL); urinary protein (11.83 g/day); and urinary sediment (20 - 29 red blood cells per high power field). On the basis of the clinical findings and biopsied lymph nodes, we diagnosed multicentric Castleman's disease (MCD). Light microscopy of kidney biopsy samples revealed various nephropathies, including membranoproliferative glomerulonephritis with crescentic formation and focal segmental sclerosis and tubulointerstitial nephritis. Immunofluorescence and electron microscopy revealed IgG-positive deposits in the subepithelial areas, mesangial areas, and tubular basement membrane. The patient's clinical findings including kidney disease improved after treatment with tocilizumab. MCD is considered to be caused by abnormally high levels of interleukin (IL)-6. Tocilizumab, an IL-6 receptor antagonist, was effective in this patient, indicating that the immune complex-related kidney findings were also related to MCD.

Emphysematous polycystic renal infection (EPRI) has a poor prognosis with conservative management, and early surgical nephrectomy has been recommended. However, percutaneous cyst drainage may be a possible treatment option. We experienced 6 patients with autosomal dominant polycystic kidney disease (ADPKD) presenting with EPRI. Three patients developed EPRI after renal transarterial embolization (TAE), and the other 3 developed EPRI independently of renal TAE. Two of the patients had only one cyst with gas formation, and the causative organism was sensitive to antibiotics; these patients were cured by cyst drainage and antibiotic therapy. However, in 3 patients with severe renal enlargement and gas formation in multiple cysts, the causative organism was antibiotic resistant and cyst drainage was not effective, so surgical nephrectomy was performed and the disease effectively treated. Surgical nephrectomy should be considered in patients with multiple cysts with gas formation and severe renal enlargement.

Introduction: Glomerular basement membrane (GBM) disease is a severe and exceedingly rare disorder characterized by the presence of circulating antibodies targeting the non-collagen NC1 domain of the α3 chain of collagen type IV in glomerular and alveolar basement membranes. It typically presents as rapidly progressive glomerulonephritis (RPGN), often accompanied by pulmonary hemorrhage. The occurrence of double-seropositivity for anti-GBM antibody and anti-neutrophil cytoplasmic antibody (ANCA), primarily with myeloperoxidase specificity (MPO-ANCA), is particularly uncommon in pediatric cases.

Case presentation: A 9-year-old boy was admitted to the pediatric ward exhibiting macroscopic hematuria, proteinuria, and acute kidney injury, with a gradual decline in kidney function. Pulmonary function remained normal. Circulating anti-GBM antibodies and ANCA, specifically targeting myeloperoxidase (MPO), were detected. Diagnosis was confirmed via percutaneous renal biopsy, which revealed circular glomerular crescents in 9 out of 16 glomeruli. Immunofluorescence examination exhibited a linear staining pattern of the capillary wall for IgG. Treatment involved 5 boluses of methylprednisolone, followed by prolonged oral prednisone, 11 plasma exchange sessions, and initiation of rituximab due to a moderate response to therapy. Subsequently, the patient's condition significantly improved, with normalized renal function observed 24 months post treatment.

Conclusion: Despite limited literature on pediatric anti-GBM and double-positive disease, it is imperative to consider these diagnoses in pediatric patients presenting with RPGN. This article offers a comprehensive summary of the main characteristics of this disease in children and emphasizes therapeutic approaches through a review of identified cases in individuals under 18 years of age.