A case of reversible splenial lesion syndrome secondary to Fanconi syndrome with white matter swelling as the main manifestation.

Reversible splenial lesion syndrome (RESLES) is a rare clinical imaging syndrome that is characterized by magnetic resonance imaging (MRI) findings of reversible abnormal signals in the splenium of the corpus callosum (SCC). There are a variety of pathogenic causes, including infection, metabolic disturbances, and antiepileptic drug use. Moreover, the disease is clinically rare and easily misdiagnosed. Here, we report a unique case of a 32-year-old man with Fanconi syndrome who had an intensified signal in the SCC and diffuse white matter swelling on MRI. We believe this to be the first adult case of RESLES as a manifestation of Fanconi syndrome, which further expands the disease spectrum leading to RESLES. The imaging features of this case included extensive lesions, symmetrical diffuse restricted signals, and reversibility. The identification of these features improves our understanding of the imaging characteristics of RESLES, thus enabling clinicians to better understand this disease, correctly establish its diagnosis, and improve its prognosis in this kind of patient.

Kidney Biopsy Findings in a Patient With Valproic Acid-Associated Fanconi Syndrome.

A 7-year-old boy with a history of febrile illness-related epilepsy syndrome presented with proteinuria and elevated creatinine. His severe epileptic disorder has been treated since age 2 with multiple antiepileptic medications, including valproic acid. More recently, he was noted to have features of Fanconi syndrome with acidosis, hypophosphatemia, hypokalemia, glucosuria, and nephrotic-range proteinuria. This was managed with supplements; however, in the setting of rising creatinine and prominent proteinuria, a kidney biopsy was performed. Renal cortex revealed markedly decreased expression of proximal tubule markers and increased expression of markers of distal nephron differentiation. Such findings have been described in several genetic and acquired conditions, including renal tubular dysgenesis, severe hypoxic injury following renal artery stenosis, and toxic injury related to in utero exposure to angiotensin-converting-enzyme inhibitors. Such changes have not been reported before in valproic acid-associated Fanconi syndrome, although in general, morphologic findings in this condition have not been well established in the literature.

Nephrolithiasis and Osteomalacia associated with adefovir-induced Fanconi syndrome in a patient with hepatitis B.

BACKGROUND: An increasing number of case reports suggest that acquired renal Fanconi syndrome may be associated with prolonged use of adefovir against hepatitis B virus. Renal Fanconi syndrome is an uncommon disease, and its complication with nephrolithiasis is quite rare. Herein, we report a rare coexistence of nephrolithiasis and acquired renal Fanconi syndrome in a chronic hepatitis B-positive patient with prolonged adefovir therapy. CASE PRESENTATION: The patient presented with osteomalacia and nephrolithiasis. Consequently, extracorporeal shock-wave lithotripsy and left double-J ureteral stent insertion were considered for obstructive nephropathy, which was caused by nephrolithiasis. However, osteomalacia had been misdiagnosed as osteoporosis before admission to our hospital. On admission, a complexity of multiple fractures, hypophosphataemia, glycosuria without hyperglycaemia and non-anion-gap metabolic acidosis indicated a diagnosis of acquired renal Fanconi syndrome induced by adefovir. After switching from adefovir to entecavir, the patient's symptoms and laboratory findings improved significantly. CONCLUSIONS: The mechanism responsible for nephrolithiasis in renal Fanconi syndrome is still unclear. We recommend regularly monitoring renal function and serum calcium and serum phosphate to prevent renal Fanconi syndrome during the prolonged use of adefovir for hepatitis B virus.

Sjögren's syndrome complicated with Fanconi syndrome and Hashimoto's thyroiditis: Case report and literature review.

We report a unique case of Sjögren's syndrome complicated with Fanconi syndrome and Hashimoto's thyroiditis in a 53-year-old Chinese woman, initially found to have proteinuria, fatigue and multiple old costal fractures. Distal tubular dysfunction is the most common renal damage in Sjögren's syndrome, while Fanconi syndrome (which is caused by proximal tubular dysfunction) and Hypothyroidism are rare complications of Sjögren's syndrome.

The HNF4A R76W mutation causes atypical dominant Fanconi syndrome in addition to a ß cell phenotype.

BACKGROUND: Mutation specific effects in monogenic disorders are rare. We describe atypical Fanconi syndrome caused by a specific heterozygous mutation in HNF4A. Heterozygous HNF4A mutations cause a beta cell phenotype of neonatal hyperinsulinism with macrosomia and young onset diabetes. Autosomal dominant idiopathic Fanconi syndrome (a renal proximal tubulopathy) is described but no genetic cause has been defined. METHODS AND RESULTS: We report six patients heterozygous for the p.R76W HNF4A mutation who have Fanconi syndrome and nephrocalcinosis in addition to neonatal hyperinsulinism and macrosomia. All six displayed a novel phenotype of proximal tubulopathy, characterised by generalised aminoaciduria, low molecular weight proteinuria, glycosuria, hyperphosphaturia and hypouricaemia, and additional features not seen in Fanconi syndrome: nephrocalcinosis, renal impairment, hypercalciuria with relative hypocalcaemia, and hypermagnesaemia. This was mutation specific, with the renal phenotype not being seen in patients with other HNF4A mutations. In silico modelling shows the R76 residue is directly involved in DNA binding and the R76W mutation reduces DNA binding affinity. The target(s) selectively affected by altered DNA binding of R76W that results in Fanconi syndrome is not known. CONCLUSIONS: The HNF4A R76W mutation is an unusual example of a mutation specific phenotype, with autosomal dominant atypical Fanconi syndrome in addition to the established beta cell phenotype.

Rachitic chest in a young adult male: Fanconi's syndrome--idiopathic type.

Presented in this paper is a case of a 36-year-old Filipino man presenting with a chronic history of intermittent proximal muscle weakness and paralysis which was associated with failure to thrive, severe bony deformities, muscle wasting and multiple electrolyte abnormalities (hypokalaemia, hypocalcaemia, hypomagnesaemia). Severe skeletal deformities led to a pathological fracture of the femoral bone and restrictive chest wall expansion during inspiration necessitating admission and consult at our institution. Correction of multiple electrolyte abnormalities was the mainstay of treatment for this case and resulted into full reversal of paralytic symptoms but skeletal and osseous abnormalities persisted. This case highlights the insidious course and subtle signs of Fanconi's syndrome leading to disfiguring skeletal deformities and abnormalities if not diagnosed early. Early suspicion and eventual diagnosis might be the key for these patients to have normal productive life devoid of crippling complications.

Tenofovir-induced Fanconi syndrome and osteomalacia in two HIV-infected patients: role of intracellular tenofovir diphosphate levels and review of the literature.

We present 2 human immunodeficiency virus-infected patients with tenofovir disoproxil fumarate-induced Fanconi syndrome, leading to osteomalacia. Intracellular tenofovir diphosphate levels were measured in 1 patient and were found to be very high, with plasma tenofovir levels just slightly elevated. Fibroblast growth factor-23, a phosphaturic hormone, was decreased in both patients and is therefore unlikely to have a pathophysiological role in this pathology. The different potential factors contributing to the development of tenofovir-related kidney proximal tubular dysfunction are discussed and the data presented may help to further elucidate its pathogenesis.

Detection of maleate-induced Fanconi syndrome by decreasing accumulation of 125I-3-iodo-alpha-methyl-L-tyrosine in the proximal tubule segment-1 region of renal cortex in mice: a trial of separate evaluation of reabsorption.

OBJECTIVE: Fanconi syndrome is a renal dysfunction characterized by various combinations of renal tubular transport dysfunction involving amino acids, glucose, protein and other substances. Most reabsorption of amino acids occurs in proximal renal tubule segment 1 (S1). The present study evaluated the possibility of early detection of drug-induced Fanconi syndrome, based on decreased renal accumulation of 125I-3-iodo-alpha-methyl-L-tyrosine (125I-IMT), an amino acid transport marker, in the S1 region of renal cortex. The present experimental model used maleate (MAL)-induced Fanconi syndrome in mice. Results were compared between 125I-IMT and 3 other clinical renal radiopharmaceuticals: 99mTc-2,3-dimercaptosuccinic acid (99mTc-DMSA); 99mTc-mercaptoacetylglycylglycylglycine (99mTc-MAG3); and 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA). METHODS: Male ddY mice (age, 6 weeks; body weight, 25 g) were used to create a Fanconi model of renal dysfunction. A single dose of maleate disodium salt was administered by intraperitoneal injection (6 mmol/kg). Hematoxylin and eosin (HE) staining of the renal cortex, renal autoradiography and measurement of renal radioactivity of labeled compounds were performed at 30, 60, 90 and 120 min after MAL injection. At 5 min after injection of labeled compounds (18.5 kBq for accumulation experiment, 670 kBq for autoradiography), animals were sacrificed by ether overdose and kidneys were removed. For the accumulation experiment, radioactivity was measured using a well-type scintillation counter. For autoradiography, 20-microm sections of frozen kidney were used with Bio-Imaging Analyzer. RESULTS: At 30 min after MAL injection, HE staining showed pyknosis in some proximal tubule cells. At that time, accumulations of 125I-IMT and 99mTc-DMSA in the S1 region were approximately 67% and 55% of control levels (p < 0.005). MAL increased accumulation of 99mTc-DTPA in the S1 region, but had no effect on accumulation of 99mTc-MAG3 in the S 1 region. CONCLUSIONS: Decreased accumulation of 123I-IMT in the S1 region appears to represent a useful marker for detection of MAL-induced Fanconi syndrome. In future, we plan to assess the efficacy of using 125I-IMT to monitor renal dysfunction induced by nephrotoxic clinical drugs.

Fanconi syndrome caused by antiepileptic therapy with valproic Acid.

PURPOSE: Valproic acid (VPA) is commonly used as an antiepileptic drug (AED). Regular screening for renal side effects is uncommon. Fanconi syndrome, a generalized dysfunction of renal proximal tubular cells, occurs with some inborn errors of metabolism. In addition, it can be acquired by exposure to several toxic substances. We report a case of Fanconi syndrome after long-term therapy with VPA. METHODS: An 8-year-old severely disabled and developmentally retarded boy with epilepsy was treated with VPA over a period of 7 years. He was hospitalized after a status epilepticus with laboratory findings suggesting a Fanconi syndrome. A PubMed-based worldwide review of the literature revealed that Fanconi syndrome is a rare side effect in children during long-term VPA treatment. We analyzed all 10 previously published cases by comparing age, underlying diseases, medication, and outcome. RESULTS: Examination revealed metabolic acidosis suggestive of renal tubular malfunction. Based on typical clinical and laboratory findings, an acquired Fanconi syndrome was diagnosed. This was treated with large doses of sodium bicarbonate. After discontinuation of VPA, renal function completely normalized within 2 months. CONCLUSIONS: Fanconi syndrome appears to be a rare but severe consequence of long-term VPA therapy. Therefore patients treated with VPA should be checked regularly for the possible development of VPA-induced Fanconi syndrome.

[Multiple pathological fractures within the scope of DeToni-Debre-Fanconi syndrome after fumarate therapy in psoriasis]. / Multiple pathologische Frakturen im Rahmen eines DeToni-Debré-Fanconi-Syndroms nach Fumarattherapie bei Psoriasis.

We report about a rare case of a pathological fracture of the shank following earlier pathological fractures at other locations in a comparatively young female patient with no history of trauma. There were no known diseases other than psoriasis. The shank fracture was treated surgically by osteosynthesis. Osteoporosis, myeloma, or malignancy as causative factors of this fracture could be excluded. Scintigraphy showed an enhancement, especially at the extremities. Other than reactive bone growth, histological examination revealed no further aspects. Laboratory analysis indicated a massive lack of vitamin D3. After transferring the patient to the internal department of our hospital, long-term medication with fumaric acid was determined to be the reason for the osteomalacia of a Fanconi's syndrome. Three months after cessation of these medicaments and treatment with active vitamin D3 metabolites, the patient was free of complaints. The radiographs showed an essential improvement of the demineralization.

Renal Fanconi syndrome: first sign of partial respiratory chain complex IV deficiency.

A 2-year-old boy who developed hypophosphatemic rickets without signs of muscular weakness or neurological disturbances is presented. Biochemical findings included hypophosphatemia, metabolic acidosis, hypouricemia, hyperphosphaturia, severe glucosuria, generalized hyperaminoaciduria, hypercalciuria, proteinuria with elevated excretion of IgG, transferrin, albumin and high levels of alpha-1-microglobulin. Urine concentration capacity and creatinine clearance were normal. Lactaturia without elevated levels of plasma lactate and a high urinary excretion of beta-hydroxybutyrate were suggestive for mitochondriopathy. Partial deficiency of cytochrome c oxidase (complex IV of the respiratory chain) was found in skeletal muscle. A renal biopsy specimen demonstrated enlarged mitochondria with abnormal arborization and disorientation of the cristae in the proximal tubular cells. Reduced activity of mitochondrial cytochrome c oxidase in tubular cells could be demonstrated by ultracytochemistry. In conclusion, rickets due to the renal Fanconi syndrome can be the first clinical sign of mitochondrial cytopathies without extra-renal symptoms. Elevated excretion of lactate and ketone bodies in urine may serve as a diagnostic marker.

Poor renal uptake of Tc-99m DMSA and Tc-99m MDP in a patient with Fanconi syndrome and near normal glomerular filtration rate.

The authors present a patient with Fanconi syndrome who demonstrated poor renal uptake of Tc-99m DMSA and high urinary concentration of the tracer. Tc-99m DTPA imaging was normal and the creatinine clearance was only minimally decreased. These findings suggest that Tc-99m DMSA may be accumulated in the kidney by glomerular filtration and subsequent tubular reabsorption. A Tc-99m MDP bone scan showed faint renal uptake, as well as diffuse high skeletal uptake, particularly in the spine, demonstrating that the metabolic bone disease associated with Fanconi syndrome can be one of the causes of poor renal visualization on a bone scan.

[Radiographic criteria of differential diagnosis of hereditary tubulopathies in children]. / Rentgenologicheskie kriterii differentsial'noi diagnostiki nasledstvennykh tubulopatii u detei.

In search for x-ray signs of skeletal involvement specific for each type of hereditary tubulopathies, the authors analyze the results of clinical and x-ray examinations of 144 children aged 2 to 16. Vitamin D-resistant rickets which was diagnosed in 83 children was found to be characterized by varus deformations of the lower limb bones, by systemic osteoporosis of various degrees with hypertrophy of the osseous beams in the epimetaphyseal compartments and accelerated bone age. In renal tubular acidosis diagnosed in 28 children the most typical findings were valgus deformation of the lower limb bones, an appreciable deceleration of bone age, systemic osteoporosis with thinning of osseous beams, the degree of bone deformation being the minimal or moderate. In 20 children with the de Toni-Debre--Fanconi disease the most frequent finding were valgus deformations of the lower limb bones, osteoporosis with drastic thinning of osseous beams unrelated to the degree of deformations and deceleration of bone age. Vitamin D-dependent rickets diagnosed in 13 children was characterized by varus deformations of the lower limb bones, hypertrophic osteoporosis, and normal parameters of bone age. Hence, our study demonstrated the possibility and high reliability of x-ray differential diagnosis of various forms of hereditary tubulopathies in children.

Poor renal uptake of technetium-99m-DMSA and technetium-99m-MDP in a patient with Fanconi syndrome and near normal glomerular filtration rate.

We present a patient with Fanconi syndrome who demonstrated poor renal uptake of 99mTc-DMSA and high urinary concentration of the tracer. A 99mTc-DTPA scan was normal and the creatinine clearance only minimally decreased. These findings suggest that 99mTc-DMSA may be accumulated in the kidney by glomerular filtration and subsequent tubular reabsorption, with the nonabsorbed fraction appearing in the urine. In Fanconi Syndrome the tubular reabsorption of DMSA may also be reduced, thus explaining the poor renal uptake in this patient. A 99mTc-MDP bone scan showed faint renal uptake and diffuse high uptake mainly in the spine, demonstrating that the metabolic bone disease associated with Fanconi Syndrome can be another mechanism for poor renal visualization on bone scan.

Renal handling of technetium-99m DMSA in rats with proximal tubular dysfunction.

The renal handling of technetium-99m dimercaptosuccinic acid ([99mTc]DMSA) was studied in rats before and after treatment with Na-maleate (2 mmol/kg i.v.). In the control period, when measured 2 hr after the intravenous injection of [99mTc]DMSA, 39.9% of the injected dose was in the kidneys and 14.6% was in the bladder. After Na-maleate treatment, only 6.4% of the injected dose of [99mTc]DMSA was retained in the kidneys while 37.9% was found in the bladder. Subsequent studies revealed that Na-maleate produced a fall in the glomerular filtration rate, the effective renal plasma flow, and a generalized proximal tubular dysfunction. The latter was characterized by polyuria and an increased excretion of glucose, protein, albumin, calcium, and inorganic phosphate. It was concluded that proximal tubular dysfunction markedly alters the renal handling of [99mTc]DMSA. Whether this augmented urinary excretion is due to an inhibition of reabsorption or an enhanced cellular efflux of [99mTc]DMSA remains to be answered.