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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 38  |  Issue : 1  |  Page : 33-36

Renal involvement in children with tuberous sclerosis


1 Department of Pediatrics, Division of Nephrology, Ege University Faculty of Medicine, İzmir, Turkey
2 Department of Pediatrics, Division of Neurology, Ege University Faculty of Medicine, İzmir, Turkey

Date of Submission28-Dec-2019
Date of Acceptance01-Apr-2020
Date of Web Publication26-Mar-2021

Correspondence Address:
Ahmet Keskinoglu
Department of Pediatrics, Division of Nephrology, Ege University Children's Hospital, Bornova, 35100, Izmir
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NSN.NSN_35_20

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  Abstract 


Objectives: Tuberous sclerosis (TS) is a multisystemic disease with a genetic component. The central nervous system is most commonly involved. Renal involvement is also common. In this study, renal involvement was investigated descriptively and analytically in children with TS. Methods: A retrospective cohort study was performed on TS patients followed in a neurology clinic. The result variable is renal involvement. Other demographic, health-related, and family characteristics were examined as independent variables. Other system involvements in children with TS were presented analytically. Descriptive and analytical statistics were performed with SPSS 24.0 software. Results: The total number of children diagnosed with TS was 52. Renal involvement was found in 9 (17.3%) of these children. Frequency of renal involvement was not statistically increased according to independent characteristics which were obtained from patient files (demographic characteristics, presence of neurological problems in the family, weight and height percentiles, and other system involvements in children with TS). Conclusion: In our study, renal involvement was found to be less frequent than the reported in the literature. It may be more relevant to conduct studies with higher number of children with TS for risk assessment of renal involvement.

Keywords: Children, renal involvement, tuberous sclerosis


How to cite this article:
Keskinoglu A, Tekgül H, Kabasakal C. Renal involvement in children with tuberous sclerosis. Neurol Sci Neurophysiol 2021;38:33-6

How to cite this URL:
Keskinoglu A, Tekgül H, Kabasakal C. Renal involvement in children with tuberous sclerosis. Neurol Sci Neurophysiol [serial online] 2021 [cited 2021 Oct 25];38:33-6. Available from: http://www.nsnjournal.org/text.asp?2021/38/1/33/311967




  Introduction Top


Tuberous sclerosis (TS) is an autosomal-dominant multisystemic disorder with the central nervous system and skin lesions. Its prevalence is estimated to be 1/6000–10,000.[1],[2] Although there are patients with good prognosis with skin findings and mild cognitive impairment, less frequently, severe cases with focal or generalized seizures or renal involvement leading to renal failure may also be seen.[3] It is also well known there are some cases, presenting severely affected cognitive functions or autism spectrum findings.[4],[5] Autism was found in 6 of 17 children diagnosed with TS in a study conducted in İzmir, Turkey.[6] Tumor-like formations called hamartomas in TS, occur in organs such as kidneys, heart, brain, lungs, and skin.[7],[8],[9]

Renal stones and cysts are encountered in children. Kidney involvement takes the first line on the leading causes of death list in adults with TS, and the second line in children, following central nervous system disorders.[10] Renal and pulmonary involvement is more common in adult patients compared to children. Kidney involvement is present in 50%–80% of all patients.

Angiomyolipomas are seen in kidneys, and about 1% of them may develop renal cell carcinoma and oncocytoma. Carcinoma is more common in adult patients.[8] Angiomyomas and cysts are the most common findings in renal involvement in children.[11],[12],[13] In a study evaluating twenty TS cases in Turkey, renal problems were found in seven cases, and no bleeding or malignancy related to the renal system was found in those cases.[14],[15]

Renal cysts in TS are seen in 15%–32% of the cases, usually small cysts; rarely, large cysts may be associated with polycystic kidney disease. Partial stenosis in the renal collecting system facilitates the formation of nephrolithiasis.[16],[17] Renal involvement should be investigated and controlled in children when TS diagnosis is established and during follow-up.

In this study, accompanying nephrological disorders of children diagnosed with TS were interpreted. The frequency of neurological involvement and their relationship with other findings were discussed.


  Methods Top


Design and data collection

This study was carried out as a retrospective cohort of children with TS, admitted to the private pediatric neurologist clinic, between the years 2006 and 2019 and followed for at least 6 months. Renal involvement and renal development disorders were the dependent variables in this retrospective cohort. Demographic data (age and gender), health history (birth weight, section/normal spontaneous delivery, birth week, and disorders at birth), and presence of neurological and nephrological problems in relatives of children with TS were obtained from the records. In addition, according to the examination findings on the records, anthropometric growth and development (weight–height percentages at the first admission), presence of motor retardation, and other signs and system effects (epilepsy, febrile or afebrile convulsions, cardiac involvement, ocular findings, and autism) were also noted.

Statistical analysis

Descriptive characteristics of all children with TS were presented with numbers and percentages for categorical variables and median (minimum–maximum value) for continuous variables with the nonparametric distribution. Chi–square analysis and Mann–Whitney U-test were used in order to determine the variables affecting renal involvement in TS. Statistical analysis was performed using IBM SPSS version 24.0. Results were considered statistically significant if P < 0.05.


  Results Top


In this study, 52 children with TS, following by a pediatric neurologist in a private practice clinic in Izmir, between 2006 and 2019 years, were evaluated retrospectively. According to the results, the median follow-up of these children was 1.5 years (minimum: 0; maximum: 13 years). The median age of the children diagnosed with TS at the time of admission was 2 years (minimum = 0; maximum = 16), and 28 (53.8%) were male. Demographic characteristics, background, and family history of 52 children with TS are shown in [Table 1].
Table 1: Demographic and family history of children with tuberous sclerosis

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At the beginning of the follow-up, 40.8% were in the 1–5 years of age group and 59.6% were born by cesarean section. Three children were reported to have problems at birth (cord entanglement and breech presentation twins). Premature birth (37 weeks and before) occurred in three children. The birth weight of four children was below 2500 g [Table 1]. Other findings and accompanying diagnoses are presented in [Table 2].
Table 2: Other associated diseases and findings in children with tuberous sclerosis

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Nine of 52 children with TS also have kidney problems. Bilateral nephrectomy and renal transplantation were performed in one of the nine children with renal disorders due to renal mass and angiomyolipomatosis. Renal angiomyoma was detected in three children except transplanted child. One of these children had bilateral angiomyomas of the size of 10 mm × 5 mm (two on the right and three on the left), and one of the other two children had at a single pole in the right kidney and the other posteriorly located angiomyoma. Subependymal giant cell astrocytoma was detected on brain magnetic resonance imaging of the child with posterior renal angiomyoma and clinically diagnosed as autism. While only one of the two children with renal cyst had multiple cortical localized cysts with the largest size of 5 mm, the other had cystic lesions with a diameter of 5 and 8 mm in the left renal collecting system. In the ultrasonography (USG) findings of two children with renal stones, there was a significant increase in both renal parenchymal echo structures and 2–3 mm stones in the other child, 2–3 mm stones in the right kidney, and an increase in medullary echogenicity in the other child. Renal functions of the child with bilateral echogenicity and pelvicaliectasis were found to be impaired. Kidney functions of eight children with renal involvement were observed to be within normal limits.

Three of the five children with cardiac findings had cardiac rhabdomyoma and two had atrial myxoma. One of the two children with eye findings had a hamartoma and the other had astrocytoma.

When renal involvement is evaluated according to the variables in [Table 3], renal involvement was more common in boys and in the presence of epilepsy. However, it was found that these two features did not significantly increase kidney involvement. It was also found that other variables examined in [Table 3] did not increase renal involvement (age, weight percentile, height percentile, family historyno, and other findingsyes) [Table 3].
Table 3: Distribution of renal involvement in tuberous sclerosis according to demographic, anthropometric, and autobiographical characteristics

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  Discussion Top


Central nervous system findings are most common in patients with TS. Most of the patients have epilepsy; half have impaired cognitive functions and learning difficulties. In our study, epilepsy was detected in 36 children (69.9%) and febrile–afebrile convulsions in 21 children (40.4%). The rate of this central nervous system finding is similar in the literature.[3],[18],[19] In our study, 3 out of 52 children with TS had autism and no renal findings.

Renal findings were common in TS, and its prevalence increases with age. Renal involvement was reported as 60% and 75% in two studies.[8],[20] In the O'Callaghan et al. study, the age distribution was between 0 and 86 years and 179 patients with TS were included, frequency of with angiomyolipoma of 69% and renal cysts with 31%.[ 8] In a study conducted in the adult group in Japan, renal involvement was found to be 71% and angiomyolipoma was detected in 61% of renal involvement and cysts were detected in 28%.[21] In another study, pediatric TS patients were followed in terms of renal involvement; the mean age of the children was 6.9 years, and the frequency of renal involvement was 55%; however, when the mean age of these children reached 10.5 years, the rate was found to be 80%, and the most common problem was angiomyolipomas.[22]

In our study, renal involvement was found to be low in only 9 (17.3%) of 52 children compared to the literature. In another study, conducted in our country, that enrolled 19 cases, detected high renal involvement (68.4%).[23] Although renal USGs of these cases were evaluated prospectively for the study, these pediatric patients were diagnosed with TS and followed up in nephrology. In our retrospective study, renal involvement was low in the patients diagnosed as TS and admitted to follow-up in the neurology clinic; moreover, this lower rate of renal involvement compared to the literature, may be due to loss to follow-up before renal evaluation was performed or renal involvement developed. Other two studies in our country have reported renal involvement between 1.1% and 77.8% as well.[24],[25]

In the study, including 167 children and adults with TS, 96 patients (57.5%) were presenting renal findings.[26] In another study in Europe, involving of 207 pediatric patients, renal findings reported in 48%.[27]

In our study, the demographic and family history characteristics of the patients were analyzed for the risk of renal involvement. There was no statistically significant increase in renal involvement. The mother of one child had TS, and there was no renal involvement in children. Renal angiolipomas, the most common finding, have been reported to increase with age in children.[28],[29] There is no study in our country detecting the risk factors that increase renal involvement.

As a result, renal involvement is common in TS children. For risk assessment of renal involvement, it is important to conduct studies with higher number of children with TS.

Acknowledgment

We would like to thank Professor Pembe Keskinoğlu for the biostatistics consultation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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