Early diagnosis of tuberous sclerosis complex – proposed guidelines for the follow-up of children with prenatal or perinatal findings of cardiac rhabdomyoma

Summary

Aim: To propose a methodology for the early diagnosis of tuberous sclerosis complex (TSC) based on an evaluation of a prospectively monitored cohort of children diagnosed with cardiac rhabdomyoma (CR). Methods: Diagnosis of TSC is both genetic and clinical, based on the presence of 11 major and 7 minor clinical criteria. At least two major features are required to confirm the diagnosis. The earliest major feature is prenatal detection of CR, while additional major features may be identified on brain MRI. Between 2019 and 2024, 17 children with a prenatal or perinatal finding of CR were monitored at the Department of Pediatric Neurology and the Children‘s Heart Centre of the Motol University Hospital. All patients underwent fetal or early postnatal echocardiography and brain MRI, with regular EEG monitoring. The children were followed from the neonatal period with the aim of diagnosing TSC and epilepsy. Results: A diagnosis of TSC was confirmed in 14 out of 17 children (83%) monitored for CR. Epilepsy manifested in 13 of the 14 TSC patients (93%), with 10 of these 13 cases occurring within the first six months of life. A care protocol for patients with prenatal or perinatal findings of CR and a recommended approach for early TSC diagnosis have been summarized in several key points. Conclusion: Examination of the fetus or newborn with CR is critical for the early diagnosis of TSC and epilepsy, enabling risk reduction for the development of epileptic encephalopathy. We propose a diagnostic methodology for TSC in the context of a prenatal or perinatal finding of CR.

Keywords:

Epilepsy – tuberous sclerosis complex (TSC) – cardiac rhabdomyoma – fetal brain MRI – fetal echocardiography – early postnatal brain MRI – early diagnosis of TSC – molecular genetic diagnosis of TSC

Introduction     

Tuberous sclerosis complex (TSC) is a disorder within the group of neurocutaneous diseases. It is a rare, congenital, autosomal dominant (AD), multisystem disease with variable clinical manifestations, characterized by the frequent occurrence of dysplastic changes or benign tumors of the central nervous system, skin, blood vessels, bones, and various organs. Malignant tumors are uncommon.

The first detailed description dates to 1880 by D. M. Bourneville, who reported autopsy findings of firm nodular lesions in the cerebral cortex and subcortical white matter and accordingly termed the disease “tuberous sclerosis” (TS) [1]. Given its multisystem involvement, the term Tuberous Sclerosis Complex” (TSC) is now preferred. By causative gene, TSC is classified as TSC1 (TSC1, encoding hamartin; 9q34; 23 exons) or TSC2 (TSC2, encoding tuberin; 16p13.3; 42 exons), with complete penetrance [2,3]. The occurrence of TSC is most commonly reported with an incidence of 1 per 6,000–10,000 live births [4]. Prevalence estimates vary: for Europe, a prevalence of 1 : 20,000 has been reported in the United Kingdom [5,6], and an overall European range of 1 : 11,300–25,000 has been cited [5,7–9].

In approximately 10–15% of patients with a clinically definite diagnosis of TSC, a causative pathogenic variant is not identified by current routine molecular genetic testing. In these cases, low-level mosaicism with a small fraction of the variant allele in blood is presumed [10]. A possible solution is the use of “high-read-depth sequencing,” which can detect mosaicism down to ~1% [10]. Approximately 60–80% of TSC cases arise from de novo pathogenic variants, while familial occurrence accounts for 20–40% of cases. The products of TSC1 and TSC2—the proteins hamartin and tuberin—form a functional complex that suppresses the activity of the mTOR (mechanistic [mammalian] target of rapamycin) kinase complex and the MAPK (mitogen-activated protein kinase) pathway. Both genes act as tumor suppressors, with major consequences for cellular growth and proliferation in target tissues, including components of the nervous system [11]. Because of the interaction within the hamartin–tuberin complex, the functional impact of both genes is partly shared, and the clinical manifestations associated with TSC1 and TSC2 are very similar, including wide variability in disease course [10]. Pathogenic variants in TSC2 are more frequent, and phenotypes associated with TSC2 tend to be more severe. Renal angiomyolipomas occur in both genotypes, whereas renal polycystic disease is observed only with TSC2. Development of epilepsy represents a major clinical complication of TSC [12].

The first modern diagnostic criteria were proposed by Gómez (1972) and later refined by Roach (1998) [13]. Subsequent revisions of the TSC diagnostic criteria were published by Northrup and Krueger in 2013 [14] and updated in 2021 [10]. The currently accepted criteria (Northrup 2021) [10] retain separate genetic and clinical components, but—unlike the 2013 criteria—without subdivision into parts A and B. A definitive diagnosis of TSC can be established by molecular identification of a pathogenic variant in TSC1 or TSC2, provided it meets American College of Medical Genetics and Genomics (ACMG) pathogenicity criteria. Despite that, clinical diagnosis remains essential. The diagnostic criteria include 11 major and 7 minor features, and TSC is established by the presence of either at least two major features or one major feature plus two or more minor features [9,10] (Table 1). The earliest major diagnostic feature is cardiac rhabdomyoma (CR), which can be detected from approximately the 20th week of gestation (earliest report at 18 weeks) [15,16] (Fig. 1). CRs are identified prenatally or perinatally (Fig. 2), and may also be detected later in life; their recognition enables diagnosis of TSC in the prenatal, neonatal, or early infant period [9,15–18]. To establish a diagnosis of TSC when CR is present, at least one additional major diagnostic feature is required. Other major features with early prenatal/perinatal manifestation are most readily detected by brain magnetic resonance imaging (MRI). Fetal brain MRI may be performed (Fig. 3a,b) or postnatal brain MRI in early infancy [10,17] (Fig. 4). Amniocentesis with subsequent molecular genetic testing is feasible, but a 10–15% false-negative rate must be considered [10].

 

Study aim: To propose a methodology for early diagnosis of tuberous sclerosis complex (TSC) based on evaluation of a prospectively followed cohort of children with cardiac rhabdomyoma (CR).

 

Table 1. Diagnostic criteria for TSC (Northrup et al., 2021) [10].

Major features Hypomelanotic macules (≥3; at least 5mm diameter) Angiofibroma (≥3) or fibrous cephalic plaque Ungual fibromas (≥2) Shagreen patch  Multiple retinal hamartomas Multiple cortical tubers and/or radial migration lines Subependymal nodule (≥2) Subependymal giant cell astrocytoma   Cardiac rhabdomyoma  Lymphangiomyomatosis (LAM)*  Angiomyolipomas (≥2)* *A combination of the 2 major clinical features LAM and angiomyolipomas without other features does not meet criteria for a definite diagnosis. Minor features “Confetti” skin lesions Dental enamel pits (≥3) Intraoral fibromas (≥2) Retinal achromic patch Multiple renal cysts Nonrenal hamartomas Sclerotic bone lesions

Definite TSC:  2 major features or 1 major feature with 2 minor features. Possible TSC:  Either 1 major feature or ≥2 minor features. Genetic diagnosis: A pathogenic variant in TSC1 or TSC2 is diagnostic for TSC. Most TSC-causing variants are sequence variants that clearly prevent TSC1 or TSC2 protein production. Some variants compatible with protein production (e.g., some missense changes) are well established as disease-causing. Other variant types should be considered with caution.

 

Study cohort and methodology 

Between 2019 and 2024, 17 children with a prenatal or perinatal finding of CR were diagnosed and followed at the Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and Motol University Hospital  (MUH), and at the Children’s Heart Centre, of the same institution. At MUH early diagnosis of TSC and epilepsy by surveillance of fetuses and neonates with CR has been implemented since 2000, in accordance with the institutional protocol [17–19]. This protocol was subsequently modified according to selected parameters of the international EPISTOP study (March 2014–October 2018), in which MUH also participated [20].

Inclusion criteria for the evaluated cohort were a prenatal or perinatal echocardiographic finding of CR (Fig. 1, 2), follow-up by a paediatric neurologist from the first month of life, and fetal brain MRI or early postnatal brain MRI performed by 4 months of age (Fig. 3, 4). A subset of parents of prospective patients were referred to a paediatric neurologist already prenatally [18].

Brain MRI was performed postnatally in all children by 4 months of age—including those with a positive finding on fetal brain MRI. The aim was to identify the most prominent dysplastic lesions (cortical tubers) that had not yet been apparent on fetal MRI. These typically represent the tuber from which epileptic activity arises, knowledge that may be highly relevant for potential future epilepsy surgery [21]. Postnatal EEG recordings were obtained—the first in the neonatal period, then monthly up to 6 months of age, every 2 months until 1 year, and thereafter every 6 months until 3 years—with the aim of detecting the development of epilepsy as early as possible [22–24] (Table 2). This EEG schedule was interrupted in the event of seizure manifestation or initiation of ASM based on EEG criteria; thereafter, EEG follow-up was performed as clinically indicated. In parallel, cranial, renal, and hepatic ultrasonography was performed and evaluated both prenatally and postnatally.

When a CR was detected, molecular genetic testing for TSC1 and TSC2 mutations was routinely indicated for the patient and their parents.                                                                                                  

 

Table 2. Methodology for early diagnosis of TSC—prenatal, perinatal, and postnatal follow-up of children with CR.                                      

Prenatal period —⁠ from the 20th week of gestation	Suspicion of CR on routine prenatal ultrasound (US) by the attending obstetrician-gynecologist—refer for fetal echocardiography
Fetal echocardiography at the Children’s Heart Centre Obstetrician-gynecologist Pediatric cardiologist Pediatric neurologist	Assessment: Determine whether the finding represents CR or another process. Assess the number of CRs and their hemodynamic significance. Evaluate arrhythmia risk The pediatric cardiologist or attending obstetrician-gynecologist informs the family about the risk of a TSC diagnosis and provides contact information for the pediatric neurologist who will conduct postnatal follow-up. Contact with the pediatric neurologist: information on the possibility of a TSC diagnosis; on the option and rationale for fetal brain MRI; and on the postnatal management plan. Prenatal referrals by the pediatric cardiologist or attending obstetrician-gynecologist: Fetal brain MRI (with parental consent). Note: ordered by OB-GYN/cardiology, as the examination pertains to the mother and fetus. Follow-up fetal echocardiography, with management according to findings. Referral to clinical genetics for TSC risk assessment, with continued follow-up postnatally.
Fetal brain MRI	TSC may be diagnosed, but the localization, extent, and character of cortical tubers are often imprecise.
Geneticist	Amniocentesis with subsequent molecular genetic testing of TSC1 and TSC2—associated with a longer turnaround time and a 10–15% false-negative rate [10].
Delivery planning	Delivery should be scheduled at a facility with a neonatal intensive care unit (NICU) and immediate access to pediatric cardiology (echocardiography) and pediatric neurology (EEG).
Perinatal period	Delivery at a prearranged facility providing multidisciplinary care (university hospital) with access to a neonatal intensive care unit (NICU).
	Examinations in the neonatal period: Cardiologist with echocardiography and ECG + management plan Pediatric neurologist with EEG + plan of further follow-up Ophthalmologic examination—fundus Transfontanelle cranial ultrasound (cUS)—with respect to TSC, only an orientational examination—and renal ultrasound (US) Genetic testing: TSC1 and TSC2
Postnatal period —further management Pediatric cardiologist Pediatric neurologist EEG brain MRI Ophthalmologist Pediatric nephrologist Nephrologist Ultrasound of the kidneys (liver) Genetics	Pediatric cardiologist—therapy (surgery for hemodynamically significant CR; sirolimus or everolimus for inoperable hemodynamically significant CR; arrhythmia management) and a long-term follow-up plan according to clinical status. Regular outpatient follow-up with EEG once a month until 6 months of age. After 6 months of age: follow-up with EEG every 2 months until 1 year of age. From 1 to 3 years of age: follow-up with EEG every 6 months. Thereafter: follow-up with EEG every 6–12 months, depending on the clinical condition. In case of epilepsy development, the above follow-up schedule is discontinued. VGB therapy is initiated, followed by additional ASM as needed for seizure control, and the patient is subsequently monitored according to clinical requirements. Brain MRI within the first 4 months of life (compared to fetal MRI, cortical tubers and cortico-subcortical dysplastic changes are better visualized). Follow-up brain MRI every 2–3 years, depending on the presence and growth dynamics of SEGA. Ophthalmologic follow-up –⁠ annual fundus examination; visual acuity assessment depending on cooperation, later visual field testing as cooperation allows. Renal (and hepatic) ultrasonography –⁠ if congenital polycystic kidney disease is not present, perform every 2–3 years until puberty, then annually or more frequently as needed. Blood pressure measurement during pediatric follow-up visits. Nephrology care as indicated by renal findings and blood pressure values. Renal (and hepatic) MRI as indicated by the nephrologist (or pediatrician). Evaluation by a clinical geneticist. If routine blood testing is negative but the clinical diagnosis of TSC is definite, consider somatic mosaicism and test additional tissues (e.g., buccal swab/saliva, affected skin or tumor), using high-coverage (deep) sequencing to detect low-level variants.

 

Results

In 3/17 (17%) children, CR was solitary; in 14/17 (83%), it was multiple. A clinical diagnosis of TSC was established in 14/17 (83%) children monitored for CR. Amniocentesis with testing for TSC1 and TSC2 was performed in 3/17 (17%) cases; a pathogenic TSC2 variant was identified in two of these patients. The third child had no molecular genetic or clinical evidence of TSC but exhibited a balanced translocation between chromosomes 16 and 19—the same finding was also detected in the clinically healthy father. No evidence suggestive of a pathogenic variant in TSC2 (located on chromosome 16) was found. In 3/17 (17%) children with CR, TSC was not established either clinically or by molecular genetics. In two of these children without a TSC diagnosis, the CR was solitary; in one child, it was multiple. Arrhythmia was treated in all three children without TSC; two (a girl with solitary CR and a boy with multiple CRs) had hemodynamically significant CR and underwent cardiac surgery. The boy with multiple CRs who lacked genetic or clinical evidence of TSC later developed epilepsy with focal seizures.

Among the 14 children with a diagnosis of TSC, CR was solitary in 1/14 (7%) and multiple in 13/14 (93%). Pathogenic variants were identified in TSC1 in 2/14 (14%) and in TSC2 in 10/14 (72%), whereas molecular genetic testing was negative in 2/14 (14%). Epilepsy occurred in 13/14 with TSC (93%), with onset from the neonatal period to 26 months (mean 7 months). Preventive VGB therapy was initiated in 2/14 (14%); one of these patients remained seizure-free thereafter. Epilepsy manifested in two age subgroups: 10/13 (77%) between the neonatal period and 6 months (mean 3 months), and 3/13 (23%) between 15 and 26 months (mean 20 months). Infantile spasms were observed in 1/13 (8%). At the end of follow-up, 4/13 (31%) were on VGB monotherapy, 4/13 (31%) on dual ASM therapy, and 5/13 (38%) on triple therapy. In 2/13 (15%) children, drug-resistant epilepsy was the indication for epilepsy surgery.

The care algorithm for patients with a prenatal or perinatal finding of CR and the recommended approach to early diagnosis of TSC were summarized as follows:

1) Echocardiography at a pediatric cardiology center to determine whether the finding represents CR or another process, to assess the number of CRs, and to evaluate the hemodynamic status.

2) In the presence of prenatal CR, fetal brain MRI may be performed to support the diagnosis of TSC; however, hamartomatous changes may not be clearly expressed prenatally; therefore, brain MRI should be repeated in infancy (by 4 months of age).

3) In cases of prenatal CR, delivery is planned at a tertiary-level center with a neonatal intensive care unit and access to a pediatric neurologist and pediatric cardiologist.

4) The newborn is examined by a cardiologist immediately after birth and, if necessary, undergoes surgery for CR or receives symptomatic treatment.

5) During neonatal hospitalization, the newborn is examined by a pediatric neurologist. Ancillary tests indicated include EEG, cranial ultrasound, and renal ultrasound. In the event of neonatal seizures or an ictal EEG recording, antiseizure treatment with VGB, the drug of choice, is initiated at 100–150 mg/kg/day in two divided doses.

6) Until 6 months of age, monthly follow-up with a pediatric neurologist and EEG is performed. Parents are instructed about possible seizure semiologies and present immediately if they occur. If seizures develop—or based on EEG criteria identified before seizure onset—preventive VGB therapy is initiated. EEG criteria comprise either focal epileptiform activity (EA) or multifocal EA. In focal EA, abnormalities are confined to one brain region but occupy ≥10% of the recording time. Multifocal EA involves two or more regions, or consists of generalized epileptiform activity, including hypsarrhythmia.

7) If epilepsy develops, brain MRI is performed under general anesthesia. If seizures do not develop, brain MRI is performed by 4 months of age.

8) Follow-up then continues monthly until 6 months of age, every two months from 6 months to 1 year, and every 6 months from 1 to 3 years (Table 2).

 

Discussion    

The clinical presentation of TSC is highly variable and reflects involvement of multiple systems (skin, nervous system, eye, bone, and visceral organs) and the presence of multiple, predominantly benign, neoplasms in various organs [2,4,10]. Diagnosis of TSC is complicated by this heterogeneity and by the variable timing of clinical manifestations [10,13,14,18]. A major improvement in diagnostic accuracy was the incorporation of molecular genetic testing results in 2013 [14]. Nonetheless, the clinical diagnostic criteria remain paramount in establishing TSC, and CR is both highly informative diagnostically and the earliest feature [3,6,9,10,17–19]. Accordingly, special attention is devoted to CR in this study. Additional diagnostic features can be identified prenatally or perinatally on brain MRI [17–19,25], where multiple cortical tubers and radial migration lines are observed in 95–100% of patients with TSC [3,10,21]. The methodology for early diagnosis of TSC targets, in the prenatal period, obstetrician-gynecologists, cardiologists, radiologists, and geneticists; in the perinatal and postnatal periods, cardiologists, pediatric neurologists, radiologists, and again geneticists. Alongside the substantial cardiological issues related to CR, the neurological aspects of TSC diagnosis and the risk of early epilepsy come to the fore [10,18,24]. TSC is established in ~50% of children with solitary CR and in ~90% of those with multiple CRs [3,10,22]. Consistent with this, our cohort showed a clear predominance of TSC among patients with multiple CRs. Epilepsy develops in 70–92% of individuals with TSC [3,20,24], with 75% manifesting by 1 year of age [24]. These findings are consistent with our cohort, in which we additionally observed two onset windows: between the neonatal period and 6 months of age, and between 15 and 21 months. Early epilepsy, including infantile spasms, may be accompanied by epileptic encephalopathy, which substantially contributes to an unfavorable neurodevelopmental outcomes [12,19,20,22]. The EPISTOP study demonstrated a significantly longer interval to first clinical seizures when antiseizure therapy was initiated upon detection of EA on EEG, and confirmed a trend toward more favorable psychomotor development in preventively treated children. In accordance with these data, we apply early treatment initiation based on EEG findings as standard clinical practice in patients with TSC (Table 2). The treatment of choice is vigabatrin (VGB) at a recommended dose of 100 mg/kg/day [18,22], up to 150 mg/kg/day [9,20,22,26]. Titration to the target dose is rapid (within one week); during up-titration, we usually administer continuous midazolam. Within the multidisciplinary team caring for patients with CR, close collaboration between the cardiologist performing fetal echocardiography and the pediatric neurologist, who counsels parents on the rationale and goals of subsequent management, is essential. Fetal brain MRI is recommended to establish the diagnosis of TSC prenatally and to evaluate structural brain changes [25]. We recommend delivery in a facility with access to a pediatric cardiologist, a pediatric neurologist, and a neonatal intensive care unit. Prenatal diagnosis of TSC is also possible by amniocentesis with molecular genetic testing targeted to TSC1 and TSC2. A drawback is a 10–15% risk of a false-negative result [9,10]. In all infants with CR, transfontanelle cranial ultrasound is performed in the neonatal period to assess ventricular size and basic brain anatomy. From a diagnostic standpoint, however, transfontanelle cranial ultrasound is frequently false-negative for TSC [17]. In all children with CR, we obtain the first postnatal brain MRI by 4 months of age; among other findings, it may reveal substantial dysplastic changes around certain tubers—often later epileptogenic [21,23,24]. This may subsequently be relevant when planning epilepsy surgery in cases of refractory epilepsy [27–29]. During the first 6 months of life, neurological evaluations with EEG are performed monthly. This is a critical period in which epilepsy most commonly manifests, and VGB therapy is initiated already upon detection of significant EA on EEG [20,22].

The neonatal assessment includes cardiology (ECG and echocardiography), renal and hepatic ultrasound, and evaluations by a clinical geneticist and an ophthalmologist. CRs may be hemodynamically significant and require cardiac surgery. For hemodynamically significant but inoperable CRs, the treatment of choice is an mTOR inhibitor—everolimus [30] or sirolimus [31]. Management also takes into account the natural history of CR, which—despite being tumors—most often regress spontaneously by the end of the toddler period [3,31] (Fig. 2). Clinically significant arrhythmias, including Wolff–Parkinson–White (WPW) syndrome, represent an important cardiologic risk [32].

On renal and hepatic ultrasound, congenital polycystic kidney disease is only rarely detected. When present, TSC2 is presumed, and nephrologists are involved in patient care [33].

 

Conclusion:

The present study proposes a methodology for early diagnosis of TSC, with the aim of emphasizing the significance of CR as the earliest diagnostic sign of TSC and the necessity of collaboration among obstetricians, neonatologists, pediatric cardiologists, and pediatric neurologists already during the prenatal and perinatal periods. Examination of a fetus, newborn, or young infant with CR is important for enabling early TSC diagnosis and early detection of the development of epilepsy. The aim of early diagnosis and therapy of epilepsy is to reduce the risk of epileptic encephalopathy in children with TSC. The methodology also includes early initiation of therapy, whereby VGB treatment may be started in a neonate or infant with TSC upon detection of significant EA on EEG. The aim of this work is to acquaint the broader professional community with the care of patients with CR and with the early diagnosis of TSC (Table 2).

 

Abbreviations:

 

Ethical principles

The study is not subject to approval by the ethics committee; patients have signed an agreement with the diagnostic and treatment process.

 

Conflict-of-Interest Statement

The authors declare that they have no conflict of interest related to the topic, preparation, or publication of this article.