Renal Manifestations of Tuberous Sclerosis Complex

The extent of kidney involvement in paediatric tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis (TSC)-associated kidney disease is a leading cause of mortality in adults with TSC. This study aimed to understand TSC features in children, particularly kidney involvement, to inform clinical care for this specific group.

METHODS

This retrospective cohort study included all paediatric (< 19 years) TSC cases at a large tertiary paediatric nephrology centre. Relevant data were collected from patients' records, statistical analyses were performed to identify associations between variables, survival probabilities were estimated with Kaplan‒Meier curves, and log-rank tests were conducted to assess survival differences among genetic mutations.

RESULTS

A total of 182 children with TSC were included. Among the 145 children with available kidney imaging data, 78.6% (114/145) exhibited kidney lesions. Angiomyolipomas (AMLs) were significantly more prevalent in the TSC2 mutation group (p = 0.018). Children with TSC2 mutations generally had poorer lesion-free survival than those with TSC1 mutations, but this difference was only significant for AMLs (p = 0.030). The change in size of largest AMLs increased with age and doubled in children above 9 years; a similar pattern was observed when stratified by genetic mutation. In contrast, kidney cysts exhibited two peaks: one in children under 5 years (2.31 mm/year) and the second in children between 15-19 years (2.82 mm/year). Chronic kidney disease was observed in 12.3% (10/81) of children, and high-risk AMLs above 3 cm were observed in 9% (13/145).

CONCLUSIONS

While TSC kidney disease emerges later in the disease course than neurological features, our findings emphasise the importance of kidney surveillance during childhood, including routine kidney imaging, kidney function, and blood pressure monitoring.

Practical Approach to Congenital Anomalies of the Kidneys: Focus on Anomalies With Insufficient or Abnormal Nephron Development: Renal Dysplasia, Renal Hypoplasia, and Renal Tubular Dysgenesis

Congenital anomalies of the kidney and urinary tract (CAKUT) accounts for up to 30% of antenatal congenital anomalies and is the main cause of kidney failure in children worldwide. This review focuses on practical approaches to CAKUT, particularly those with insufficient or abnormal nephron development, such as renal dysplasia, renal hypoplasia, and renal tubular dysgenesis. The review provides insights into the histological features, pathogenesis, mechanisms, etiologies, antenatal and postnatal presentation, management, and prognosis of these anomalies. Differential diagnoses are discussed as several syndromes may include CAKUT as a phenotypic component and renal dysplasia may occur in some ciliopathies, tumor predisposition syndromes, and inborn errors of metabolism. Diagnosis and genetic counseling for CAKUT are challenging, due to the extensive variability in presentation, genetic and phenotypic heterogeneity, and difficulties to assess postnatal lung and renal function on prenatal imaging. The review highlights the importance of perinatal autopsy and pathological findings in surgical specimens to establish the diagnosis and prognosis of CAKUT. The indications and the type of genetic testing are discussed. The aim is to provide essential insights into the practical approaches, diagnostic processes, and genetic considerations offering valuable guidance for pediatric and perinatal pathologists.

Circulating biomarkers of kidney angiomyolipoma and cysts in tuberous sclerosis complex patients

Patients with tuberous sclerosis complex (TSC) develop multi-organ disease manifestations, with kidney angiomyolipomas (AML) and cysts being one of the most common and deadly. Early and regular AML/cyst detection and monitoring are vital to lower TSC patient morbidity and mortality. However, the current standard of care involves imaging-based methods that are not designed for rapid screening, posing challenges for early detection. To identify potential diagnostic screening biomarkers of AML/cysts, we performed global untargeted metabolomics in blood samples from 283 kidney AML/cyst-positive or -negative TSC patients using mass spectrometry. We identified 7 highly sensitive chemical features, including octanoic acid, that predict kidney AML/cysts in TSC patients. Patients with elevated octanoic acid have lower levels of very long-chain fatty acids (VLCFAs), suggesting that dysregulated peroxisome activity leads to overproduction of octanoic acid via VLCFA oxidation. These data highlight AML/cysts blood biomarkers for TSC patients and offers valuable metabolic insights into the disease.

[Kidney involvement in rare hereditary diseases]

Various rare inherited disorders can be associated with kidney involvement, including glomerulopathies, tubulopathies, multiple cysts, congenital anomalies of the kidneys and urinary tract, urolithiasis, malignant and benign tumors. Genetic nephropathy should be always considered in children, adolescents and young patients with the kidneys or urinary tract disorders and/or patients with positive family anamnesis. Extrarenal manifestations can be a valuable clue for diagnosis of certain hereditary diseases, e.g. neurosensory deafness in Alport syndrome or photofobia in nephropathic cystinosis. Diagnosis of monogenic inherited diseases should be verified by genetic testing. Specific drugs are available for treatment of certain hereditary diseases involving kidney, e.g. Fabry disease, cystinosis, primary hyperoxaluria I type and atypical hemolytic uremic syndrome.

Characteristic morphology and immunohistochemical patterns of clear cell papillary renal cell tumours may be observed in renal cell carcinomas, a critical pitfall in renal biopsy cytopathology

BACKGROUND

Clear cell papillary renal cell tumour (CCPRCT) was renamed from previous clear cell papillary renal cell carcinoma (CCPRCC) in the latest WHO Classification of Tumours. It is essential to differentiate RCC from CCPRCT in renal mass biopsies (RMB).

DESIGN

RMB cases with subsequent resections were reviewed. The pathology reports and pertinent clinical information were recorded.

RESULTS

Fifteen cases displaying either CCPRCT morphology (20% diffuse, 67% focal) or immunohistochemical patterns (cup-like CA9: 20% diffuse, 47% focal; CK7: 33% diffuse, 40% focal) were identified. One case was positive for TFE3. TSC mutation was identified in one case. Both cases exhibited both CCPRCT morphology and immunohistochemical patterns for CA9 and CK7, with focal high-grade nuclei. RMB diagnoses were as follows: 6 (40%) as CCRCC, 2 (13%) as CCPRCT, 2 (13%) as CCRCC versus CCPRCT, 2 (13%) as CCRCC versus PRCC, 1 (7%) as RCC with TSC mutation versus CCPRCT, 1 (7%) as TFE3-rearranged RCC versus PRCC, and 1 (7%) as cyst with low-grade atypia. 71% of patients underwent nephrectomy, 21% received systemic treatment for stage 4 RCCs, and 7% with ablation for small renal mass (1.6 cm) with low-grade CCRCC.

CONCLUSIONS

Our study highlights that morphologic and immunochemical features of CCPRCT may be present in RCCs, including RCC-TFE3 expression and TSC-associated RCC, a critical pitfall to misdiagnose aggressive RCC as indolent CCPRCT and result in undertreatment. Careful examination of morphology and immunostains for CA9, CK7, and TFE3, as well as molecular tests, is crucial for distinguishing aggressive RCC from indolent CCPRCT.

Predominantly multiple focal non-cystic renal lesions: an imaging approach

Multiple non-cystic renal lesions are occasionally discovered during imaging for various reasons and poses a diagnostic challenge to the practicing radiologist. These lesions may appear as a primary or dominant imaging finding or may be an additional abnormality in the setting of multiorgan involvement. Awareness of the imaging appearance of the various entities presenting as renal lesions integrated with associated extrarenal imaging findings along with clinical information is crucial for a proper diagnostic approach and patient work-up. This review summarizes the most relevant causes of infectious, inflammatory, vascular, and neoplastic disorders presenting as predominantly multiple focal non-cystic lesions.

Nutritional status as a predictive factor for paediatric tuberous sclerosis complex-associated kidney angiomyolipomas: a retrospective analysis

The purpose of this study is to determine the predictive factors of tuberous sclerosis complex (TSC)-associated kidney disease and its progression in children. Retrospective review of children with TSC in a tertiary children's hospital was performed. Relevant data were extracted, and Cox proportional hazards regression was used to establish predictors of kidney lesions. Logistic regression was conducted to identify factors predicting chronic kidney disease (CKD) and high-risk angiomyolipomas (above 3 cm). Kidney imaging data were available in 145 children with TSC; of these, 79% (114/145) had abnormal findings. The only significant predictive factor for cyst development was being female (HR = 0.503, 95% CI 0.264-0.956). Being female (HR = 0.505, 95% CI 0.272-0.937) and underweight (HR = 0.092, 95% CI 0.011-0.800) both lowers the risk of having angiomyolipomas, but TSC2 mutations (HR = 2.568, 95% CI 1.101-5.989) and being obese (HR = 2.555, 95%CI 1.243-5.255) increases risks. Ten (12%) of 81 children with kidney function tested demonstrate CKD stages II-V, and only angiomyolipomas above 3 cm predict CKD. Additionally, 13/145 (9%) children had high-risk angiomyolipomas, whereby current age (adjusted odds ratio (aOR) 1.015, 95% CI 1.004-1.026) and being overweight/obese (aOR 7.129, 95% CI 1.940-26.202) were significantly associated with angiomyolipomas above 3 cm.

CONCLUSIONS

While gender and genotype are known predictors, this study includes the novel finding of nutritional status as a predictor of TSC-associated kidney disease. This study sheds light on a possible complex interplay of hormonal influences, obesity, and kidney angiomyolipomas growth, and further investigations focusing on the impact of nutritional status on TSC-associated kidney disease are warranted.

WHAT IS KNOWN

• Gender and genotype are well-studied predictive factors in TSC kidney disease.

WHAT IS NEW

• Nutritional status may influence the development and the progression of kidney lesions in children with TSC and should not be overlooked. • Management guidelines of TSC-associated kidney disease can address nutritional aspects.

Review of the spectrum of tuberous sclerosis complex: The Saudi Arabian Experience

OBJECTIVES

To determine the prevalence of tuberous sclerosis complex (TSC) in the paediatric Saudi population and to characterise the range of clinical symptoms, neurocutaneous findings, neuroimaging results, and complications of the disease.

METHODS

A total of 61 genetically confirmed TSC patients from the National Guard Health Affairs (NGHA) in Saudi Arabia were the subject of this retrospective descriptive analysis. The data were presented using descriptive measures.

RESULTS

The mean age at diagnosis was found to be 4.9 years. Subependymal nodules (86.9%), numerous cortical tubers and/or radial migration lines (63.9%), and hypomelanotic macules (63.9%) were the 3 most common significant criteria. The vast majority (86.9%) of those diagnosed had epilepsy, of which 50% were considered medically intractable. Nearly half of our subjects underwent genetic testing, which revealed that TSC2 predominated over TSC1. Symptoms of Tuberous Sclerosis Complex-Associated Neuropsychiatric Disorders (TAND) were present in 66.7% of TSC1 patients and 73.9% of TSC2 patients.

CONCLUSION

The findings of this study demonstrate that the clinical spectrum of TSC among Saudi children is consistent with the body of existing literature. The TSC2 was more prevalent than TSC1. The most frequent signs were cutaneous and neurological. Monitoring TSC patients regularly is crucial to identify any issues as soon as possible.

Behavioral and Psychiatric Disorders in Syndromic Autism

Syndromic autism refers to autism spectrum disorder diagnosed in the context of a known genetic syndrome. The specific manifestations of any one of these syndromic autisms are related to a clinically defined genetic syndrome that can be traced to certain genes and variants, genetic deletions, or duplications at the chromosome level. The genetic mutations or defects in single genes associated with these genetic disorders result in a significant elevation of risk for developing autism relative to the general population and are related to recurrence with inheritance patterns. Additionally, these syndromes are associated with typical behavioral characteristics or phenotypes as well as an increased risk for specific behavioral or psychiatric disorders and clinical findings. Knowledge of these associations helps guide clinicians in identifying potentially treatable conditions that can help to improve the lives of affected patients and their families.

Clinical outcomes of fetuses with cardiac rhabdomyoma: A case series from a tertiary center

AIMS

The study aims to evaluate the genetic and clinical outcomes of fetal cardiac rhabdomyoma in our tertiary center.

METHODS

Data of cases with cardiac rhabdomyoma detected by fetal echocardiography during antenatal follow-up were analyzed retrospectively.

RESULTS

Nine cases were included in the study. The incidence of cardiac rhabdomyoma was 0.003%. The median fetal diagnosis time was 26th weeks, the most common location was the LV. There was no hemodynamic disorder requiring cardiovascular intervention in any of the cases. Of the eight genetically tested cases, four were tuberous sclerosis complex (TSC) gene-negative, one hereditary TSC2, one de novo TSC1, and two de novo TSC2 gene mutants. Postnatal first-year survival rate of the cases was 88.8%.

CONCLUSIONS

Cardiac rhabdomyoma is a rare fetal and pediatric pathology that generally is a remarkable finding in the clinical process of TSC. Therefore, cases should be evaluated multisystemically and genetic counseling should be given to the family.

The Pathophysiology of Inherited Renal Cystic Diseases

Renal cystic diseases (RCDs) can arise from utero to early adulthood and present with a variety of symptoms including renal, hepatic, and cardiovascular manifestations. It is well known that common RCDs such as autosomal polycystic kidney disease and autosomal recessive kidney disease are linked to genes such as PKD1 and PKHD1, respectively. However, it is important to investigate the genetic pathophysiology of how these gene mutations lead to clinical symptoms and include some of the less-studied RCDs, such as autosomal dominant tubulointerstitial kidney disease, multicystic dysplastic kidney, Zellweger syndrome, calyceal diverticula, and more. We plan to take a thorough look into the genetic involvement and clinical sequalae of a number of RCDs with the goal of helping to guide diagnosis, counseling, and treatment.

Bilateral renal angiomyolipoma with left renal artery aneurysm in tuberous sclerosis: case report and literature review

Introduction and importance

Tuberous sclerosis disorder (TSD) is a rare genetic disease that causes abnormal growths or tumors in various organs of the body. They are usually benign and asymptomatic. However, severe, rapidly growing tuberous sclerosis can be fatal. Renal angiomyolipomas are commonly associated with TSD, which can be further worsened by the presence of aneurysms and put the patient at risk for life-threatening hemorrhage.

Case presentation

A 29-year-old female presented to the emergency room complaining of right flank pain with an unknown past medical history of tuberous sclerosis. The patient was suspected to have TSD as she fulfilled one of the major features of TSD required to establish a possible diagnosis. On computed tomography scan imaging, bilateral fat-density nodules were revealed in both kidneys. The largest is 7 cm in the left kidney, located at the upper pole, and was associated with a bleeding aneurysm measuring 4 cm in diameter. While the other fatty nodule was recorded at 6 cm in the right kidney at the lower pole.

Clinical discussion

After evaluation, the patient was planned for diagnostic catheterization of the left kidney, through which selective angiography of the left kidney was done, and eventually, selective embolization of the branch supplying the left angiomyolipoma was performed.

Conclusion

The authors finally conclude that thorough investigations, including systemic manifestations, must be taken into consideration when suspecting tuberous sclerosis, and a conservative approach must always be prioritized before taking any decision toward invasive approaches.

Tuberous Sclerosis Complex Kidney Lesion Pathogenesis: A Developmental Perspective

The phenotypic diversity of tuberous sclerosis complex (TSC) kidney pathology is enigmatic. Despite a well-established monogenic etiology, an incomplete understanding of lesion pathogenesis persists. In this review, we explore the question: How do TSC kidney lesions arise? We appraise literature findings in the context of mutational timing and cell-of-origin. Through a developmental lens, we integrate the critical results from clinical studies, human specimens, and genetic animal models. We also review novel insights gleaned from emerging organoid and single-cell sequencing technologies. We present a new model of pathogenesis which posits a phenotypic continuum, whereby lesions arise by mutagenesis during development from variably timed second-hit events. This model can serve as a conceptual framework for testing hypotheses of TSC lesion pathogenesis, both in the kidney and in other affected tissues.

Tuberous Sclerosis Complex with Renal Stones and Distal Renal Tubular Acidosis: Case Report and Literature Review

Distal renal tubular acidosis (RTA) is a common cause of renal stones and nephrocalcinosis in children. Distal RTA can be either acquired or congenital because of a genetic defect. Tuberous sclerosis complex is an autosomal dominant inherited neurocutaneous syndrome with variable renal involvement. We describe a case of a six-year-old boy with tuberous sclerosis complex who developed distal RTA and renal stones.

Cystic kidney diseases in children

Cystic kidney disease comprises a broad group of heterogeneous diseases, which differ greatly in age at onset, disease manifestation, systemic involvement, disease progression, and long-term prognosis. As our understanding of these diseases continues to evolve and new treatment strategies continue to emerge, correctly differentiating and diagnosing these diseases becomes increasingly important. In this review, we aim to highlight the key features of the most relevant cystic kidney diseases, underscore important diagnostic characteristics of each disease, and present specific management options if applicable.

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.

Renal organoid modeling of tuberous sclerosis complex reveals lesion features arise from diverse developmental processes

Tuberous sclerosis complex (TSC) is a multisystem tumor-forming disorder caused by loss of TSC1 or TSC2. Renal manifestations predominately include cysts and angiomyolipomas. Despite a well-described monogenic etiology, the cellular pathogenesis remains elusive. We report a genetically engineered human renal organoid model that recapitulates pleiotropic features of TSC kidney disease in vitro and upon orthotopic xenotransplantation. Time course single-cell RNA sequencing demonstrates that loss of TSC1 or TSC2 affects multiple developmental processes in the renal epithelial, stromal, and glial compartments. First, TSC1 or TSC2 ablation induces transitional upregulation of stromal-associated genes. Second, epithelial cells in the TSC1^-/- and TSC2^-/- organoids exhibit a rapamycin-insensitive epithelial-to-mesenchymal transition. Third, a melanocytic population forms exclusively in TSC1^-/- and TSC2^-/- organoids, branching from MITF⁺ Schwann cell precursors. Together, these results illustrate the pleiotropic developmental consequences of biallelic inactivation of TSC1 or TSC2 and offer insight into TSC kidney lesion pathogenesis.

A rare case of tuberous sclerosis complex-associated renal cell carcinoma

Renal cell carcinoma is rarely described in paediatric patients with tuberous sclerosis complex. This report describes a case of an 11-year-old male with tuberous sclerosis-associated renal cell carcinoma.

Renal Oncocytoma: The Diagnostic Challenge to Unmask the Double of Renal Cancer

Renal oncocytoma represents the most common type of benign neoplasm that is an increasing concern for urologists, oncologists, and nephrologists due to its difficult differential diagnosis and frequent overtreatment. It displays a variable neoplastic parenchymal and stromal architecture, and the defining cellular element is a large polygonal, granular, eosinophilic, mitochondria-rich cell known as an oncocyte. The real challenge in the oncocytoma treatment algorithm is related to the misdiagnosis due to its resemblance, at an initial radiological assessment, to malignant renal cancers with a completely different prognosis and medical treatment. Unfortunately, percutaneous renal biopsy is not frequently performed due to the possible side effects related to the procedure. Therefore, the majority of oncocytoma are diagnosed after the surgical operation via partial or radical nephrectomy. For this reason, new reliable strategies to solve this issue are needed. In our review, we will discuss the clinical implications of renal oncocytoma in daily clinical practice with a particular focus on the medical diagnosis and treatment and on the potential of novel promising molecular biomarkers such as circulating microRNAs to distinguish between a benign and a malignant lesion.

[Epithelioid angiomyolipoma of the kidney after successfully treated malignant melanoma]

Hintergrund

Die Therapie der epitheloiden Angiomyolipome (eAML) kann eine Herausforderung darstellen, da bei dieser sehr seltenen Unterform der gutartigen mesenchymalen Angiomyolipome anders als bei den klassischen Angiomyolipomen bei bis zu 30 % der Fälle Lymphknotenmetastasen, lokale Rezidive und Fernmetastasen auftreten.

Ziel der Arbeit

Wir berichten hier nach unserer Recherche erstmals in Deutschland von einem Fall von eAML nach stattgehabtem malignem Melanom.

Material und Methoden

Neben der Klinik und Histologie wird die genetische Untersuchung des Tumorgewebes dargestellt.

Ergebnisse

Es fand sich eine somatische, trunkierende Mutation des TSC2-Gens („tuberous sclerosis complex“) im Angiomyolipom.

Schlussfolgerung

Die Beziehung zu verwandten Tumorentitäten in der histologischen Diagnostik wird dargestellt und eine mögliche Rolle der genetischen Diagnostik für die Therapieplanung diskutiert.

Enhancing disease awareness for tuberous sclerosis complex in patients with radiologic diagnosis of renal angiomyolipoma: an observational study

Background

Tuberous Sclerosis Complex (TSC) is a genetic disorder, with renal manifestations like angiomyolipoma (AML) occurring in 70–80% of patients. AML usually cause more complications in TCS patients than in non-TSC patients. However, AML patients are not routinely investigated for TSC. Our aim was to retrospectively assess the correlation between radiologically diagnosed AML and TSC.

Methods

All patients were stratified into AML related vs. unrelated to TSC. Correlations were calculated to determine the association between age, AML, and TSC.

Results

Complete data were available for 521 patients with renal AML, in 7 of which the concurrent diagnosis of TSC was found. Younger age significantly positively correlated with the prevalence of TSC in AML patients (p <  0.01). 37 (7%) of the 521 patients were within the age-range of 18–40 years, in which TSC occurred in 6 cases, 4 (66.7%) of which presented with multiple, bilateral renal AML (p <  0.05), and 2 (33.3%) of which with a single, unilateral AML (p <  0.05). In patients with AML but without TSC, unilateral AML was found in 83.9% and bilateral AML in 16.1% (p <  0.05). Simple binary logistic regression analysis revealed bilateral AML (OR 33.0; 95% CI 3.2–344.0; p = 0.003) (but not unilateral AML (OR 0.09; 95% CI 0.01–0.88; p = 0.04)) to be a risk factor for TSC.

Conclusions

The presence of bilateral AML in patients within the age-range of 18–40 years should raise suspicion for TSC as the underlying cause. Therefore, our advice is to refer patients with multiple bilateral renal AML for further investigations regarding TSC.