Imaging features of tuberous sclerosis complex with autosomal-dominant polycystic kidney disease: a contiguous gene syndrome

Atypical noncontiguous TSC2/PKD1 gene deletions presenting as tuberous sclerosis/polycystic kidney disease contiguous gene syndrome

Tuberous sclerosis complex (TSC) and autosomal dominant polycystic kidney disease (ADPKD) are genetically distinct disorders typically associated with pathogenic variants in TSC1 and TSC2 for the former and PKD1 and PKD2 for the latter. TSC2 and PKD1 lie adjacent to each other, and large deletions comprising both genes lead to TSC2/PKD1 contiguous gene deletion syndrome (CGS). In this study, we describe a young female patient exhibiting symptoms of TSC2/PKD1 CGS in which genetic analysis disclosed two noncontiguous partial gene deletions in TSC2 and PKD1 that putatively are responsible for the manifestations of the syndrome. Further analysis revealed that both deletions appear to be de novo on the maternal chromosome, presumably with a germline origin. Despite extensive analysis, no maternal chromosomal rearrangement triggering these pathogenic variants was detected. This case elucidates a unique pathogenesis for TSC2/PKD1 CGS, diverging from the common contiguous deletions typically observed, marking the first reported instance of TSC2/PKD1 CGS caused by independent, functionally significant partial gene deletions.

Update on the Application of Ultrasonography in Understanding Autosomal Dominant Polycystic Kidney Disease

With an estimated prevalence of 1 in 1000 individuals globally, autosomal dominant polycystic kidney disease (ADPKD) stands as the most prevalent inherited renal disorder. Ultrasonography (US) is the most widely used imaging modality in the diagnosis and monitoring of ADPKD. This review discusses the role of US in the evaluation of ADPKD, including its diagnostic accuracy, limitations, and recent advances. An overview of the pathophysiology and clinical manifestations of ADPKD has also been provided. Furthermore, the potential of US as a noninvasive tool for the assessment of disease progression and treatment response is examined. Overall, US remains an essential tool for the management of ADPKD, and ongoing research efforts are aimed at improving its diagnostic and prognostic capabilities.

Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases: Five-year Experience of a Pediatric Tertiary Hospital in Portugal

INTRODUCTION

Neurocutaneous syndromes (NCS) are a heterogeneous group of conditions with multiorgan involvement and diverse manifestations, evolving throughout life with significant morbidity. A multidisciplinary approach to NCS patients has been advocated, although a specific model is not yet established. The aim of this study was 1) to describe the organization of the recently created Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases (MOCND) at a Portuguese pediatric tertiary hospital; 2) to share our institutional experience focusing on the most common conditions, neurofibromatosis type 1 (NF1) and tuberous sclerosis complex (TSC); 3) to analyze the advantages of a multidisciplinary center and approach in NCS.

METHODS

Retrospective analysis of 281 patients enrolled in the MOCND over the first five years of activity (October 2016 to December 2021), reviewing genetics, family history, clinical features, complications, and therapeutic strategies for NF1 and TSC.

RESULTS

The clinic works weekly with a core team of pediatricians and pediatric neurologists supported by other specialties as needed. Of the 281 patients enrolled, 224 (79.7%) had identifiable syndromes such as NF1 (n = 105), TSC (n = 35), hypomelanosis of Ito (n = 11), Sturge-Weber syndrome (n = 5), and others. In NF1 patients, 41.0% had a positive family history, all manifested café-au-lait macules, 38.1% neurofibromas with 45.0% being large plexiform neurofibromas. Sixteen were under treatment with selumetinib. Genetic testing was performed in 82.9% of TSC patients with pathogenic variants found in TSC2 gene in 72.4% patients (82.7% if considered contiguous gene syndrome). Family history was positive in 31.4%. All TSC patients presented hypomelanotic macules and fulfilled diagnostic criteria. Fourteen patients were being treated with mTOR inhibitors.

CONCLUSION

Offering a systematic and multidisciplinary approach to NCS patients enables timely diagnosis, promotes a structured follow-up, and encourages discussion to outline management plans for optimal care to every patient, with significant impact on the quality of life of patients and families.

Cystic kidney disease in tuberous sclerosis complex: current knowledge and unresolved questions

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with an estimated incidence of one in 5000 to 10,000 live births worldwide. Two million people of all races and genders are estimated to have TSC secondary to mutations in one of two tumor suppressor genes, TSC1 or TSC2. The respective TSC1 and 2 gene products - hamartin and tuberin - form cytoplasmic heterodimers that inhibit mTOR-mediated cell growth and division. When mTOR inhibition is lost, people with TSC develop characteristic and usually benign tumors in various organ systems. Kidney tumors and cysts are common, particularly in the setting of TSC2 gene mutations. In most TSC patients, the number of kidney cysts is limited, their morphology is simple, their size is small, and their clinical significance is negligible. In some, cyst morphology progresses from simple to complex with the risk of malignant transformation. In others, aggressive accumulation and growth of kidney cysts can cause hypertension, impaired kidney function, and progression to kidney failure. This educational review summarizes current knowledge and remaining open questions regarding cystic kidney disease in TSC, emphasizing detection, classification, surveillance, and treatment options.

The Importance of Genetic Testing in the Differential Diagnosis of Atypical TSC2-PKD1 Contiguous Gene Syndrome—Case Series

Background: In clinical practice, the possible diagnosis of tuberous sclerosis or polycystic kidney disease is primarily based on clinical criteria, which can later be verified by genetic testing. But in the case of TSC2/PKD1 contiguous gene syndrome (TSC2/PKD1-CGS), the renal appearance of the disease is more serious. Therefore, early genetic analysis is recommended. Methods: Herein we present the report of four children with TSC2/PKD1-CGS, one involving the NTHL1 gene. We aim to emphasize the importance of genetic testing in this rare syndrome. Results: During the follow-up of tuberous sclerosis and polycystic kidney disease patients, it is essential to reappraise the diagnosis if the clinical symptoms’ appearance or onset time is unusual. Targeted genetic testing is recommended. However, early tumor formation necessitates the extension of genetic analysis. Conclusions: An appropriate evaluation of the phenotype is the cornerstone of diagnosing the rare TSC2/PKD1-CGS with the help of genetic results. In addition, malignant tumors could draw attention to an infrequent large deletion.

TSC2/PKD1 contiguous deletion syndrome in a pregnant woman: A case report

TSC2/PKD1 contiguous gene deletion syndrome is a disease caused by the deletions of the TSC2 and PKD1 genes. This is a rare contiguous genomic disease with clinical manifestations of tuberous sclerosis and polycystic kidney disease. To our knowledge, this case report is the first known case of TSC2/PKD1 contiguous gene deletions in a pregnant woman. The patient had multiple renal cysts, angiomyolipoma, hypomelanotic macules, shagreen patch, subependymal giant cell astrocytoma, multiple cortical tubers, and subependymal nodules. The patient underwent genetic testing. To exclude genetic defects in the fetus, prenatal fetal genetic testing was performed after obtaining the patient's consent. We found an increasing trend in the size of renal cysts and renal angiomyolipomas in patients with polycystic kidney with tuberous sclerosis during pregnancy. Through enhanced clinical monitoring of patients and prenatal genetic testing of the fetus, timely and effective clinical intervention for the mother may be achieved, thus obtaining the best possible outcome for both mother and fetus.

Utility of contrast-enhanced ultrasound for solid mass surveillance and characterization in children with tuberous sclerosis complex: an initial experience

BACKGROUND

Patients with tuberous sclerosis complex (TSC) can develop solid kidney masses from childhood. Imaging surveillance is done to detect renal cell carcinoma (RCC) and angiomyolipomas (AML), including AMLs at risk for hemorrhage. Intravenous contrast-enhanced ultrasound (CEUS) may be useful for screening as ultrasound is well tolerated by children and ultrasound contrast agents (UCA) are not nephrotoxic.

METHODS

Retrospective review of kidney CEUS exams of pediatric TSC patients. Qualitative CEUS analysis by consensus of 3 radiologists assessed rate, intensity, and pattern of lesion enhancement. Quantitative CEUS analysis was performed using Vuebox®. Where available, abdominal MRI was analyzed qualitatively for the same features and quantitatively by in-house-developed software. Time-intensity curves were generated from both CEUS and MRI where possible. Appearance of lesions were compared between CEUS and MRI and histology where available.

RESULTS

Nine masses in 5 patients included one histologically proven RCC and 8 AMLs diagnosed by imaging. Quantitative CEUS of RCC showed malignant features including increased peak enhancement 162%, rapid wash-in rate 162%, and elevated washout rate 156% compared to normal kidney tissue; versus AML which was 68%, 105%, and 125%, respectively. All masses were hypoenhancing on MRI compared to normal kidney tissue; MR dynamic contrast study offered no distinction between RCC and AML. The only MRI feature differentiating RCC from AML was absence of fat.

CONCLUSION

Temporal resolution afforded by CEUS was useful to distinguish malignant from benign kidney masses. CEUS may prove useful for screening, characterizing, and follow-up of kidney lesions in pediatric TSC patients.

Abdominal ultrasonographic manifestations in pediatric patients with tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare genetic disease which leads to formation of benign tumors in the brain and other organs of the body. Ultrasound (US) can detect the location, quantity, size and internal echo of TSC-associated renal diseases, liver angiomyolipoma (AML), and co-existing lesions, providing important diagnostic basis for clinical diagnosis. The aim of the present study was to investigate the abdominal ultrasonographic features of pediatric TSC and explore the advantages of abdominal ultrasonography in clinical practice.

METHODS

Data of children with TSC, who presented to the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, between January 2016 and November 2018, were analyzed by a retrospective chart review. The cases were identified from electronic medical records (EMR) system and underwent ultrasonography, we yielded a total of 12 patients.

RESULTS

The 12 pediatric patients, including 5 boys and 7 girls, ranged in age from 9 months to 13 years old. And they all had a history of epilepsy. All the patients underwent brain magnetic resonance imaging (MRI) or computed tomography (CT) examination, which revealed a scattered distribution of multiple hyperintense nodules. Of the 12 patients, 10 had TSC-associated bilateral renal AMLs, 5 had hepatic AML, and 4 had renal cysts.

CONCLUSIONS

US is a useful and non-invasive tool for the detection of TSC-associated renal and liver lesions and for clinical follow-up among pediatric patients.

Recommendations for the management of renal involvement in the tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a rare, hereditary, multisystemic disease with a broad phenotypic spectrum. Its management requires the collaboration of multiple specialists. Just as in the paediatric age, the paediatric neurologist takes on special importance; in adulthood, renal involvement is the cause of the greatest morbidity and mortality. There are several recommendations on the general management of patients with TSC but none that focuses on renal involvement. These recommendations respond to the need to provide guidelines to facilitate a better knowledge and diagnostic-therapeutic management of the renal involvement of TSC through a rational use of complementary tests and the correct use of available treatments. Their elaboration has been based on consensus within the hereditary renal diseases working group of the SEN/REDINREN (Spanish Society of Nephrology/Kidney Research Network). It has also counted on the participation of non-nephrologist specialists in TSC in order to expand the vision of the disease.

Imaging of Kidney Cysts and Cystic Kidney Diseases in Children: An International Working Group Consensus Statement

Kidney cysts can manifest as focal disease (simple and complex kidney cysts), affect a whole kidney (eg, multicystic dysplastic kidney or cystic dysplasia), or manifest as bilateral cystic disease (eg, autosomal recessive polycystic kidney disease [ARPKD] or autosomal dominant polycystic kidney disease [ADPKD]). In children, as opposed to adults, a larger proportion of kidney cysts are due to genetic diseases (eg, HNF1B nephropathy, various ciliopathies, and tuberous sclerosis complex), and fewer patients have simple cysts or acquired cystic kidney disease. The purpose of this consensus statement is to provide clinical guidance on standardization of imaging tests to evaluate kidney cysts in children. A committee of international experts in pediatric nephrology, pediatric radiology, pediatric US, and adult nephrology prepared systematic literature reviews and formulated recommendations at a consensus meeting. The final statement was endorsed by the European Society of Pediatric Radiology, the European Federation of Societies for Ultrasound in Medicine and Biology, the European Society of Pediatric Nephrology, and reviewed by the European Reference Network for Rare Kidney Diseases. Main recommendations are as follows: US is the method of choice when assessing pediatric kidney cysts, with selected indications for MRI and contrast-enhanced US. CT should be avoided whenever possible because of ionizing radiation. Renal US yields essential diagnostic information in many cases. In patients with ARPKD or other ciliopathies, abdominal US is needed for diagnosis and screening of portal hypertension. US is usually sufficient for follow-up kidney imaging, but MRI can be valuable for clinical trials in patients with ADPKD or in older children with tuberous sclerosis complex to evaluate both kidney cysts and angiomyolipomas.

Thoracoabdominal imaging of tuberous sclerosis

Imaging of tuberous sclerosis complex has rapidly evolved over the last decade in association with increased understanding of the disease process and new treatment modalities. Tuberous sclerosis complex is best known for the neurological symptoms and the associated neuroimaging findings, and children with tuberous sclerosis complex require active surveillance of associated abnormalities in the chest, abdomen and pelvis. Common findings that require regular imaging surveillance are angiomyolipomas in the kidneys and lymphangioleiomyomatosis in the chest. However multiple rarer associations have been attributed to tuberous sclerosis complex and should be considered by radiologists reviewing any imaging in these children. In this review the authors discuss the spectrum of imaging findings in people with tuberous sclerosis complex, focusing on MR imaging findings in the chest, abdomen and pelvis.

Hereditary Renal Cystic Disorders: Imaging of the Kidneys and Beyond

The purpose of this article is to review the hereditary renal cystic diseases that can manifest in children and adults, with specific attention to pathogenesis and imaging features. Various common and uncommon hereditary renal cystic diseases are reviewed in terms of their underlying etiology, including the involved genetic mutations and the affected proteins and cellular structures. Focus is placed on the morphologic findings in each condition and the features that distinguish one disorder from another. The two most common categories of hereditary renal cystic disease are (a) the ciliopathic disorders, which are related to mutations affecting the primary cilia (called "ciliopathies"), and (b) the phakomatoses. Autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, and the "medullary cystic disease complex" are all ciliopathies but have different phenotypes. Tuberous sclerosis complex and the associated "contiguous gene syndrome," as well as von Hippel-Lindau syndrome, are phakomatoses that can manifest with cystic renal lesions but have uniquely different extrarenal manifestations. Finally, DICER1 mutations can manifest with renal cystic lesions (typically, cystic nephromas) in patients predisposed to other malignancies in the chest, ovaries, and thyroid. Although some overlap exists in the appearance of the renal cysts associated with each of these diseases, there are clear morphologic differences (eg, cyst size, location, and complexity) that are emphasized in this review. To improve patient outcomes, it is important for the radiologist to recognize the various hereditary renal cystic diseases so that a correct diagnosis is assigned and so that the patient is adequately evaluated and followed up. ^©RSNA, 2017.

Beyond polycystic kidney disease

Tuberous sclerosis(TS) is an autosomal dominant disease caused by mutations in TSC1 and TSC2 genes. TSC2 gene is located in chromosome 16p13.3, adjacent to PKD1 gene, responsible for the autosomal dominant polycystic kidney disease. In a rare subgroup of patients, the presence of a deletion which simultaneously affects the TSC2 and PKD1 genes has been confirmed. TSC2/PKD1-Contiguous Gene Syndrome is characterised by the early appearance of autosomal dominant polycystic kidney disease in combination with several phenotypic manifestations of TS. We present a 13-year-old girl with bilateral renal cysts detected at the age of 9 months. At the age of 13, she was referred to the Dermatology Outpatients Clinic due to a facial cutaneous eruption. She presented with facial erythema, fibroadenomas with malar distribution and disseminated hypomelanotic macules, meeting the criteria for TS. TSC2/PKD1 Contiguous Gene Syndrome deletion was suspected, being later confirmed by genetic testing.

Treatment of renal angiomyolipoma in tuberous sclerosis complex (TSC) patients

In adult tuberous sclerosis complex (TSC) patients, renal complications are the leading cause of death. Beginning in childhood, up to 80 % of patients develop renal angiomyolipoma characterized by a size-dependent risk of life-threatening bleeding. After discovery of the two causative genes, TSC1 and TSC2, and the role of mammalian target of rapamycin (mTOR) regulation in the pathogenesis of TSC, an increasing number of clinical studies evaluating mTOR inhibition in TSC patients have shown impressive results in many organ manifestations, such as brain, lung, and kidney. For renal angiomyolipoma, mTOR inhibitor treatment fundamentally changed the approach from preventive embolization or even partial nephrectomy to everolimus treatment in order to preserve kidney function.

Evolving Strategies in the Treatment of Tuberous Sclerosis Complex-associated Angiomyolipomas (TSC-AML)

Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic disorder characterized by the development of numerous benign tumors that occur in multiple organ systems throughout the lifetime of the affected individuals. Renal angiomyolipomas occur in up to 80% of TSC patients, and chronic kidney disease from increasing tumor burden is the primary cause of TSC-related mortality. Our review evaluates evidence for localized and systemic therapy in the management of TSC-angiomyolipomas. Urologists or nephrologists experienced in TSC disease should coordinate the care of TSC patients with renal involvement to improve care and reduce costs.