Medullary sponge kidney

Intriguing association between type 1 diabetes mellitus, Gitelman syndrome and Cacci-Ricci disease: Triad of rare diseases: A case report

We report the case of a patient who exhibits a concurrent diagnosis of type 1 diabetes mellitus, Gitelman syndrome and Cacci-Ricci disease. A 27-year-old male patient was diagnosed with Gitelman syndrome at the age of 3 years. Fourteen years later, he developed an autoantibody-negative type 1 diabetes mellitus. Cacci-Ricci's disease was revealed by terminal hematuria and considered in view of the appearance found on the computed tomography (CT) scan. The finger-prick blood glucose level was 6 g/dl with no acetonuria. Creatinine clearance was 60 ml/min. Thyroid function tests were normal. Calcium, phosphorus and parathormone (PTH) levels were normal. Discussion: Gitelman syndrome is a rare disorder. The association between Gitelman syndrome and type 1 diabetes mellitus has been reported in the literature in two patients. Authors have investigated the association between Gitelman syndrome and type 2 diabetes mellitus. Several pathophysiological explanations have been put forward. Cacci-ricci disease is a rare, benign congenital anomaly. No association between type 1 diabetes mellitus, Gitelman syndrome and Cacci-Ricci disease has been reported in the literature. To our knowledge, this is the first case described in the literature.

Diagnosis and treatment of bilateral adrenal pheochromocytoma with RET gene mutation combined with medullary sponge kidney: A case report

RATIONALE

Pheochromocytomas are a group of tumors with high genetic heterogeneity, and the clinical characteristics of rearranged during transfection (RET)-mutated pheochromocytoma with medullary spongiform kidney are rarely studied. The treatment process of 1 patient with bilateral adrenal pheochromocytoma combined with medullary sponge kidney with RET gene mutation in our department was retrospectively analyzed, and the treatment methods for this type of disease were studied and summarized in combination with relevant literature.

PATIENT CONCERNS

In this case, the patient was found to have bilateral adrenal masses for 8 years due to physical examination, and intermittent dizziness and discomfort for 2 years. Imaging and related laboratory examinations suggest bilateral adrenal giant pheochromocytoma with bilateral medullary sponge kidney. RET gene testing was performed on the patient and his descendant after signing the informed consent form.

DIAGNOSES

The patient was diagnosed with bilateral adrenal pheochromocytoma with a RET proto-oncogene mutation and a bilateral medullary spongy kidney.

INTERVISION AND OUTCOMES

After sufficient perioperative preparation, retroperitoneal laparoscopic bilateral adrenal pheochromocytoma resection was performed by stages. The operation was successful, and hormone replacement therapy was performed after the operation, with regular follow-up. Relevant genetic testing revealed that the c.1900T > C: p.C634R mutation was detected in the patient's RET gene, which was a heterozygous missense mutation, and the mutation was also present in the son of his family. A literature analysis found that pheochromocytoma is a tumor with high genetic heterogeneity, and the RET proto-oncogene is a common pathogenic gene for bilateral adrenal pheochromocytoma. Medullary sponging of kidneys is a rare complication of this disease.

LESSONS

On the basis of adequate perioperative preparation, surgical resection is the most effective and preferred treatment for this type of disease. Laparoscopic surgery is minimally invasive, safe, and effective by stages. Mutations in the RET proto-oncogene may lead to medullary spongy kidneys in multiple endocrine neoplasia 2.

Hypokalemic Periodic Paralysis Secondary to Medullary Sponge Kidney Complicated With Renal Tubular Acidosis

Hypokalemic periodic paralysis has a high risk of life-threatening dysrhythmias. Hyperchloremic acidosis with hypokalemia is a dangerous condition. There are several causes of hypokalemia, in addition to common diseases, such as hyperthyroidism, hyperaldosteronism, and Cushing’s syndrome; the other rare diseases include renal tubular acidosis (RTA), Bartter’s syndrome, and Gitelman’s syndrome. We present an unusual case of hypokalemic periodic paralysis, which was caused by a medullary sponge kidney with distal RTA. The patient had no significant medical history and was not taking any conventional drugs. Investigations demonstrated a combination of hypokalemia, hyperchloremia, metabolic acidosis with a normal anion gap, relatively raised urinary pH, and decreased phosphate level. Results suggested a diagnosis of RTA with secondary hyperparathyroidism. After potassium citrate replacement and correction of acidosis, the patient’s condition was in remission. This case highlights the rare etiology of hypokalemia and the need to actively search for the pathogenesis of unexplained hypokalemia to avoid delaying the condition.

Medullary sponge kidney: unusual finding in kidney transplant recipient

Background

Medullary sponge kidney is generally considered a benign condition, gold standard for the diagnosis is urography but it has almost been replaced by UroCT that did not present the same sensibility. Although it is really rare, our sonography’s findings were consistent with medullary sponge kidney in the transplanted kidneys.

Case presentation

A 45-year-old woman with a long history of double-kidney transplantation complained of frequent urinary tract infections, a history of vague loin pain and came to our attention for sonography follow-up. Her kidney function was normal, we did not find signs of infections in the transplanted kidneys and urinary findings were normal. Curiously, the transplanted kidneys came from a newborn and the patient received a double-kidney transplantation in order to guarantee a satisfactory renal function.

Conclusions

Despite a long history of kidney transplantation, genetic disease should not be forgotten when symptoms and images recall to specific inherited alterations. Sonography has to be considered in diagnostic path of kidney cystic disease.

Single-Cell Gene Expression Analysis in Patients with Medullary Sponge Kidney and a Retrospective Study

OBJECTIVE

To establish better diagnosis thinking and provide advanced understanding of MSK, the CT imaging features, clinical characteristics, and the expression of suspected genes in the kidney spatiotemporal immune zonation and fetal renal development were investigated.

METHODS

17 patients with MSK hospitalized in our hospital were selected as our research subjects. Human Phenotype Ontology, MalaCards: The Human Disease Database, GeneCards: The Human Gene Database, Human Protein Atlas, and Single Cell Expression Atlas were used to analyze this disease.

RESULTS

In our 17 patients, the incidence of MSK tended to be the same in male and female, and the onset age of MSK was probably 31-50 years old. The top one related disease of MSK was nephrocalcinosis and the most frequent phenotype related to MSK was nephrolithiasis. In addition, the expression of HNF1B, CLCN5, GDNF, ATP6V0A4, ATP6V1B1, LAMA2, RET, ACAN, and ABCC8 has been implicated in both human kidney immune zonation and fetal kidney development.

CONCLUSIONS

HNF1B, CLCN5, GDNF, ATP6V0A4, ATP6V1B1, LAMA2, RET, ACAN, and ABCC8 could be independent indicators for the diagnosis and preventive intervention of MSK patients, and abnormal kidney development due to mutations in key genes was the underlying cause of MSK.

Analysis of urinary exosomes applications for rare kidney disorders

Introduction: Exosomes are nanovesicles that play important functions in a variety of physiological and pathological conditions. They are powerful cell-to-cell communication tool thanks to the protein, mRNA, miRNA, and lipid cargoes they carry. They are also emerging as valuable diagnostic and prognostic biomarker sources. Urinary exosomes carry information from all the cells of the urinary tract, downstream of the podocyte. Rare kidney diseases are a subset of an inherited diseases whose genetic diagnosis can be unclear, and presentation can vary due to genetic, epigenetic, and environmental factors. Areas covered: In this review, we focus on a group of rare and often neglected kidney diseases, for which we have sufficient available literature data on urinary exosomes. The analysis of their content can help to comprehend pathological mechanisms and to identify biomarkers for diagnosis, prognosis, and therapeutic targets. Expert opinion: The foreseeable large-scale application of system biology approach to the profiling of exosomal proteins as a source of renal disease biomarkers will be also useful to stratify patients with rare kidney diseases whose penetrance, phenotypic presentation, and age of onset vary sensibly. This can ameliorate the clinical management.

Ultrasound to address medullary sponge kidney: a retrospective study

Background

Medullary sponge kidney (MSK) is a rare disease characterized by cystic dilatation of papillary collecting ducts. Intravenous urography is still considered the gold standard for diagnosis. We identified a cohort of patients from our outpatient clinic with established diagnosis of MSK to outline some ultrasonographic characteristics that may help establish a diagnosis.

Methods

We conducted a retrospective study of patients seen between January 1st 2009 and January 1st 2019 in our clinic. Out of 4321 patients, 18 had a diagnosis of MSK. We reviewed their clinical and family history, laboratory data and imaging studies. Specifically, we focused on ultrasound imaging.

Results

Patients were referred to our outpatient clinic because of renal impairment (44%), family history of nephropathy (17%), nephrolithiasis or an established diagnosis of MSK (39%). Seventy-two percent of patients presented with chronic kidney disease, 22% required hemodialysis. Urinary tract infections (44%), nephrolithiasis (33%), microscopic hematuria (50%) and proteinuria (44%) were reported. Seven patients underwent computed tomography; all of them received ultrasound. Ultrasound examination showed bilateral renal cysts, usually small and located in the renal medulla, and microcalcifications located in the medulla or within the cysts.

Conclusion

We identified a peculiar tetrad associated with MSK: 1) hypoechoic medullary areas, 2) hyperechoic spots, 3) microcystic dilatation of papillary zone, 4) multiple calcifications (linear, small stones or calcified intracystic sediment) in each papilla. The presence of this diagnostic tetrad, added to laboratory data and clinical history, could be helpful in the differential diagnosis to identify patients with MSK.

Ambiguous clear cell carcinoma in medullary sponge kidney: A case report

Medullary sponge kidney (MSK) is a characteristic renal malformation, with a relatively low incidence. Radiologically, identification of MSK is sometimes ambiguous when compared to a renal mass. Here, we report a novel renal clear cell carcinoma in MSK, and discuss our approach to treatment. We recommended that a preoperative biopsy should be performed, followed by a comprehensive discussion regarding the appropriate perioperative preparations and careful surgical techniques that should be performed for this complex disease.

Proteomic Analysis of Urinary Microvesicles and Exosomes in Medullary Sponge Kidney Disease and Autosomal Dominant Polycystic Kidney Disease

BACKGROUND AND OBJECTIVES

Microvesicles and exosomes are involved in the pathogenesis of autosomal dominant polycystic kidney disease. However, it is unclear whether they also contribute to medullary sponge kidney, a sporadic kidney malformation featuring cysts, nephrocalcinosis, and recurrent kidney stones. We addressed this knowledge gap by comparative proteomic analysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The protein content of microvesicles and exosomes isolated from the urine of 15 patients with medullary sponge kidney and 15 patients with autosomal dominant polycystic kidney disease was determined by mass spectrometry followed by weighted gene coexpression network analysis, support vector machine learning, and partial least squares discriminant analysis to compare the profiles and select the most discriminative proteins. The proteomic data were verified by ELISA.

RESULTS

A total of 2950 proteins were isolated from microvesicles and exosomes, including 1579 (54%) identified in all samples but only 178 (6%) and 88 (3%) specific for medullary sponge kidney microvesicles and exosomes, and 183 (6%) and 98 (3%) specific for autosomal dominant polycystic kidney disease microvesicles and exosomes, respectively. The weighted gene coexpression network analysis revealed ten modules comprising proteins with similar expression profiles. Support vector machine learning and partial least squares discriminant analysis identified 34 proteins that were highly discriminative between the diseases. Among these, CD133 was upregulated in exosomes from autosomal dominant polycystic kidney disease and validated by ELISA.

CONCLUSIONS

Our data indicate a different proteomic profile of urinary microvesicles and exosomes in patients with medullary sponge kidney compared with patients with autosomal dominant polycystic kidney disease. The urine proteomic profile of patients with autosomal dominant polycystic kidney disease was enriched of proteins involved in cell proliferation and matrix remodeling. Instead, proteins identified in patients with medullary sponge kidney were associated with parenchymal calcium deposition/nephrolithiasis and systemic metabolic derangements associated with stones formation and bone mineralization defects.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_04_24_CJASNPodcast_19_06_.mp3.

Nephrocalcinosis in adolescent girl with medullary sponge kidney and mild hemihypertrophy: A case report

RATIONALE

Medullary sponge kidney (MSK) is a rare congenital abnormality characterized by cystic dilatation of the medullary collecting tubules. The disorder is likely to be complicated by nephrocalcinosis, urolithiasis, tubular dysfunctions, and urinary tract infections. In addition, it may be rarely associated with extrarenal anomalies.

PATIENT CONCERN

We present a case of 17-year old girl who was referred for metabolic evaluation of bilateral nephrocalcinosis. Physical examination showed signs of mild, left-sided hemihypertrophy involving the lower limb, buttock, trunk, face, and tongue. The imaging studies of kidneys including intravenous urography and contrast computed tomography showed numerous medullary calcification and a typical picture of MSK-"paint brush"/"bouquet of flowers" appearance of the dilated tubules within the renal medulla. Laboratory evaluation revealed sterile pyuria, hypercalciuria, and hypocitraturia.

INTERVENTION

The patient was subsequently treated with potassium citrate, hydrochlorothiazide, low sodium and low oxalate diet accompanied by high fluid intake.

OUTCOMES

After a 1-year therapy the normalization of calciuria and citraturia occurred and no progression of nephrocalcinosis was observed.

LESSONS

We conclude that MSK should always be considered as a cause of nephrocalcinosis. Since the final diagnosis requires specific imaging techniques, the concomitant extrarenal abnormalities such as hemihypertrophy may facilitate diagnostic decisions.

Living kidney donation from people at risk of nephrolithiasis, with a focus on the genetic forms

Deciding whether to accept a donor with nephrolithiasis is a multifaceted task because of the challenge of finding enough suitable donors while at the same time ensuring the safety of both donors and recipients. Until not long ago, donors with a history of renal stones or with stones emerging during screening on imaging were not considered ideal, but recent guidelines have adopted less stringent criteria for potential donors at risk of stones. This review goes through the problems that need to be approached to arrive at a wise clinical decision, balancing the safety of donors and recipients with the need to expand the organ pool. The risk of declining renal function and worsening stone formation is examined. Documents (consensus statements, guidelines, etc.) on this issue released by the most important medical societies and organizations are discussed and compared. Specific problems of living kidney donation associated with certain systemic (chronic hypercalcemia due to CYP24A1 gene mutations, primary hyperoxaluria, APRT deficiency) and renal (medullary sponge kidney, cystinuria, distal renal tubular acidosis, Dent's disease, Bartter syndrome, familial hypomagnesemia with hypercalciuria and nephrocalcinosis) Mendelian disorders that cause nephrolithiasis are also addressed.

Efficacy of Multi-Detector Computed Tomography for the Diagnosis of Medullary Sponge Kidney

Objective

To expand the diagnostic armamentarium for medullary sponge kidney (MSK), we evaluate the use of high-resolution multidetector computed tomography (MDCT) for MSK diagnosis and compare to the standard intravenous urography (IVU). Despite a significant prevalence amongst stone formers, diagnosis of this well described condition has declined. IVU, the gold standard in MSK diagnosis, has largely been replaced by CT, which has previously been shown unable to demonstrate signs of MSK.

Methods and Materials

Patients with known history of MSK based on IVU underwent limited MDCT urogram. Control group patients, without MSK, also had MDCT urograms performed for other clinically indicated conditions. Studies were scored by board-certified radiologists on a 0-2 scale based on the likelihood of MSK. IVU studies, when available, were similarly graded.

Results

MDCT was diagnostic of MSK in 9 out of the 10 patients with known history of MSK. No false positives were present in our series. The one case of MSK not detected on MDCT was graded as a "1" on its respective IVU. Sensitivity and specificity were 90 and 100%, respectively, when compared with IVU.

Conclusion

Concordance with IVU findings, despite a small reduction in sensitivity, indicates MDCT to be a suitable, and more readily available replacement for IVU in the diagnosis of MSK.

Outcomes of living kidney donors with medullary sponge kidney

BACKGROUND

Patients with medullary sponge kidney (MSK) commonly encounter recurrent nephrolithiasis. The existing knowledge on safety of donors with MSK has not been studied.

METHODS

We conducted a retrospective cohort study at a tertiary referral hospital to assess the outcomes of living kidney donors with MSK. All adults with MSK (N = 26) who underwent nephrectomy as living kidney donors between January 2000 and September 2014 were included. Non-donors with MSK (N = 78) were randomly selected by matching the year of birth and the comorbidity score with a ratio of 1:3 for comparison.

RESULTS

The incident rates of symptomatic stone were 0.7, 0.4 and 4.9 events/100 patient-years in donors, recipients and non-donors, respectively. After adjusting for history of kidney stones and baseline estimated glomerular filtration rate (eGFR), the kidney stone-related event was significantly lower in donors than in non-donors (hazard ratio 0.14; 95% confidence interval 0.01-0.66). One recipient of MSK living donor had symptomatic stone at median follow-up time of 8.4 years (interquartile range 5.6-12.4 years). None of MSK donors had hypercalciuria, hypocitraturia or hyperoxaluria prior to kidney donation. At 5 years after the index surgery date, there was no significant difference in eGFR between donors and non-donors (76.1 versus 70.9 mL/min/1.73 m², P = 0.12).

CONCLUSIONS

These findings are reassuring for the safety of MSK kidney donors with normal kidney function, low kidney stone risk and no significant comorbidity.

Biopsy proven medullary sponge kidney: clinical findings, histopathology, and role of osteogenesis in stone and plaque formation

Medullary sponge kidney (MSK) is associated with recurrent stone formation, but the clinical phenotype is unclear because patients with other disorders may be incorrectly labeled MSK. We studied 12 patients with histologic findings pathognomonic of MSK. All patients had an endoscopically recognizable pattern of papillary malformation, which may be segmental or diffuse. Affected papillae are enlarged and billowy, due to markedly enlarged inner medullary collecting ducts (IMCD), which contain small, mobile ductal stones. Patients had frequent dilation of Bellini ducts, with occasional mineral plugs. Stones may form over white (Randall's) plaque, but most renal pelvic stones are not attached, and have a similar morphology as ductal stones, which are a mixture of calcium oxalate and apatite. Patients had no abnormalities of urinary acidification or acid excretion; the most frequent metabolic abnormality was idiopathic hypercalciuria. Although both Runx2 and Osterix are expressed in papillae of MSK patients, no mineral deposition was seen at the sites of gene expression, arguing against a role of these genes in this process. Similar studies in idiopathic calcium stone formers showed no expression of these genes at sites of Randall's plaque. The most likely mechanism for stone formation in MSK appears to be crystallization due to urinary stasis in dilated IMCD with subsequent passage of ductal stones into the renal pelvis where they may serve as nuclei for stone formation.

Calcium phosphate stone morphology can reliably predict distal renal tubular acidosis

PURPOSE

Calcium stones represent 85% to 90% of all urinary calculi, including various crystalline compositions and etiological conditions. Calcium phosphate accounts for 10% to 15% of cases. These stones are mainly related to 3 groups of risk factors, including calcium or phosphate metabolism disturbance, renal acidification defects and urinary tract infection. Identifying the stone etiology often requires extensive metabolic evaluation. We assessed whether stone analysis including morphological typing in addition to stone composition could be a valuable help for diagnosis.

MATERIALS AND METHODS

Of 60,564 stones analyzed by morphological examination and infrared spectroscopy at our laboratory 6,439 (10.6%) were mainly composed of carbapatite. Of these stone 1,093 patients were included in study who had an available etiological diagnosis and stones containing at least 70% of calcium phosphate without struvite.

RESULTS

Of the 1,093 calcium phosphate stones 12.8% showed a peculiar morphology termed IVa2, characterized by a smooth aspect and a glazed brown-yellow appearance with tiny cracks. IVa2 morphology was observed in 96.1% of stones associated with inherited distal renal tubular acidosis. In contrast, the other stones of similar composition but different morphology were related to distal renal tubular acidosis in only 3.9% of cases. In addition, IVa2 stones were found in 65% of calcium phosphate stone formers associated with Sjögren syndrome and in 35% of calcium phosphate stones in patients with medullary sponge kidney. These 2 conditions are related to a mild to moderate distal acidification defect.

CONCLUSIONS

Identifying IVa2 stone morphology is clinically relevant because it should prompt clinicians to search for complete or incomplete distal acidosis and initiate specific therapy to decrease recurrence.

CT urography for the diagnosis of medullary sponge kidney

BACKGROUND

Medullary sponge kidney (MSK) is characterized by malformation of the terminal collecting ducts and is associated with an increased risk of nephrolithiasis, nephrocalcinosis, urinary tract infections, renal acidification defects, and reduced bone density. It has been historically diagnosed with intravenous pyelography (IVP), which is falling out of favor as an imaging modality. CT urography (CTU) performed with multidetector CT (MDCT) has been shown to create images of the renal collecting system with similar detail as IVP; however, its utility in diagnosing MSK has not been defined.

CASE REPORT

We present the first 15 patients with recurrent symptomatic nephrolithiasis who were evaluated in our renal stone clinic with CTU. Four patients were diagnosed with MSK after visualization of the characteristic radiologic findings.

DISCUSSION

CTU effectively demonstrates the characteristic radiologic findings of MSK including collecting tubule dilatation, medullary nephrocalcinosis, nephrolithiasis, and medullary cysts. Dose reduction protocols can reduce radiation exposure below that associated with conventional IVP. We propose CTU be considered for the diagnosis of MSK.