Tuberous sclerosis complex and myocardial fat-containing lesions: a report of four cases

Tuberous Sclerosis: Current Update

Tuberous sclerosis complex (TSC) is a relatively rare autosomal dominant neurocutaneous disorder secondary to mutations in the TSC1 or TSC2 tumor suppressor genes. Although manifestation of the classic triad of seizures, intellectual disability, and facial angiofibromas may facilitate timely diagnosis of TSC, the multisystem features that may indicate TSC in the absence of these manifestations remain highly variable. In addition, patients with TSC are at risk of developing multiple benign and malignant tumors in various organ systems, resulting in increased morbidity and mortality. Thus, imaging plays a critical role in diagnosis, surveillance, and management of patients with TSC. It is crucial that radiologists be familiar with TSC and the various associated imaging features to avoid a delayed or incorrect diagnosis. Key manifestations include cortical dysplasias, subependymal nodules, subependymal giant cell astrocytomas, cardiac rhabdomyomas, lymphangioleiomyomatosis, and angiomyolipomas. Renal angiomyolipomas in particular can manifest with imaging features that mimic renal malignancy and pose a diagnostic dilemma. Other manifestations include dermatologic and ophthalmic manifestations, renal cysts, renal cell carcinomas, multifocal micronodular pneumocyte hyperplasia, splenic hamartomas, and other rare tumors such as perivascular epithelioid tumors. In addition to using imaging and clinical features to confirm the diagnosis, genetic testing can be performed. In this article, the molecular pathogenesis, clinical manifestations, and imaging features of TSC are reviewed. Current recommendations for management and surveillance of TSC are discussed as well. ^©RSNA, 2021.

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.

Fatty Images of the Heart: Spectrum of Normal and Pathological Findings by Computed Tomography and Cardiac Magnetic Resonance Imaging

Ectopic cardiac fatty images are not rarely detected incidentally by computed tomography and cardiac magnetic resonance, or by exams focused on the heart as in general thoracic imaging evaluations. A correct interpretation of these findings is essential in order to recognize their normal or pathological meaning, focusing on the eventually associated clinical implications. The development of techniques such as computed tomography and cardiac magnetic resonance allowed a detailed detection and evaluation of adipose tissue within the heart. This pictorial review illustrates the most common characteristics of cardiac fatty images by computed tomography and cardiac magnetic resonance, in a spectrum of normal and pathological conditions ranging from physiological adipose images to diseases presenting with cardiac fatty foci. Physiologic intramyocardial adipose tissue may normally be present in healthy adults, being not related to cardiac affections and without any clinical consequence. However cardiac fatty images may also be the expression of various diseases, comprehending arrhythmogenic right ventricular dysplasia, postmyocardial infarction lipomatous metaplasia, dilated cardiomyopathy, and lipomatous hypertrophy of the interatrial septum. Fatty neoplasms of the heart as lipoma and liposarcoma are also described.

Pathology, imaging, and treatment of cardiac tumours

Cardiac tumours are a rare, but often devastating, clinical diagnosis. They encompass a broad set of lesions that include both neoplastic and non-neoplastic conditions. Cardiac tumours are often diagnosed incidentally during work-up for other conditions, or during ultrasound, CT, or MRI scans for unusual or nonspecific symptoms. In the past decade, important changes have been made in the nomenclature and the recommendations for diagnosis of cardiac tumours, as highlighted by the WHO's 2015 revision of the classification of cardiac tumours. Moreover, important advances in molecular genetics and therapeutics offer new approaches for the diagnosis and treatment of affected patients. In this Review, we provide an overview of the clinical, pathological, and imaging characteristics of all types of cardiac masses, including both benign and malignant primary cardiac neoplasms.

Myocardial Fatty Foci in Adult Patients with Tuberous Sclerosis Complex: Association with Gene Mutation and Multiorgan Involvement

PURPOSE

To estimate the association between myocardial fatty foci (MFF) on chest computed tomographic (CT) images and type of gene mutation or multiorgan involvement in patients with tuberous sclerosis complex (TSC).

MATERIALS AND METHODS

This retrospective case-control study was approved by the ethics committee, which waived the need for patient consent. Forty-eight patients with definite TSC (41 women; mean age, 35 years ± 11 [standard deviation]) and 96 age- and sex-matched patients without TSC who had undergone chest CT were evaluated. Two blinded readers independently scored MFF as low-attenuation areas within the myocardium. Patient history, gene mutation, and multiorgan involvement were obtained from clinical records. Cohen κ, Mann-Whitney U, χ(2) or Fisher exact, Kruskal-Wallis, and Spearman statistics were calculated.

RESULTS

One or more MFF was detected in 50% (24 of 48) of patients with TSC; however, no MFF was detected in control patients (P < .001). MFFs were oval (62%, 15 of 24) or linear (38%, nine of 24) and involved the left ventricle in 13 patients and both ventricles in 24 patients (mostly the apical or midleft ventricle); median size was 127 mm(2). After four patients with TSC and unknown mutational status (two with MFF) were excluded, MFF was detected in 53% (10 of 19) of patients with TSC1 mutation, 65% (11 of 17) of patients with TSC2 mutation, and 12% (one of eight) of patients with TSC but without an identified mutation (P = .044). MFF presence was associated with brain (P = .011) and multiorgan (P = .008) involvement. The number of MFF per patient correlated with the degree of multiorgan involvement (P = .014). With MFF considered predictive of TSC, 50% (24of 48) sensitivity, 100% (96 of 96) specificity, 100% (24 of 24) positive predictive value, and 80% (96 of 120) negative predictive value were obtained.

CONCLUSION

MFF was highly specific for TSC. MFF presence was associated with TSC gene mutations and with brain or multiorgan involvement; their number per patient was correlated with the degree of multiorgan involvement.

Cardiac CT angiography beyond the coronary arteries: what radiologists need to know and why they need to know it

OBJECTIVE

With current state-of-the-art CT combining fast scanning times and high spatial resolution, anatomy beyond the coronary arteries is well visualized and may lead to discovery of abnormalities. The purpose of this article is to provide a strategy for radiologists to recognize important extracoronary cardiac CT angiography (CTA) findings.

CONCLUSION

A systemic approach to cardiac CTA by anatomic location and attention to key CT features are critical to identify and properly characterize important extracoronary cardiac abnormalities.

Cardiac fat-containing lesions are common in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a highly variable, multisystem, genetic disorder that affects approximately 1:6,000 individuals. It has previously been thought that the cardiac manifestation of TSC is congenital rhabdomyomas, which occur during infancy and typically regress during childhood. Recently, there have been findings of cardiac fat-containing lesions in adult TSC patients that appear distinct from the presence of cardiac rhabdomyomas. We review the chest CT scans of 73 individuals with TSC to check for cardiac fat-containing lesions. Fat-containing lesions were found in the heart of approximately one-third of adolescents and adults with TSC. In this population with cardiac fat-containing lesions, no statistically significant difference was observed between the genders and between the different mutation types. Compared to those without cardiac fat findings, those with cardiac fat were more than twice as likely to have another abdominal manifestation of TSC. The results indicate that it may be appropriate to consider these cardiac fat foci as a clinical criterion for the diagnosis of TSC, given their frequency in our population. Our findings also suggest that a relation exists between the cardiac fat-containing lesions and other abdominal angiomyolipomas. More research regarding these cardiac fat-containing lesions is needed to better characterize their origin and clinical significance.

Histological diagnosis of cardiac lipoma in an adult with tuberous sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disorder caused by mutations in either of the two genes, TSC1 or TSC2, which code for the proteins hamartin and tuberin, respectively. These proteins act as tumour-growth suppressors with mutations in their genes leading to multiple hamartomatous growths throughout the central nervous system, lungs, heart, kidneys, eyes and skin. There have been reports of patients with TSC having an increased incidence of cardiac neoplasms, especially rhabdomyomas. A much smaller proportion of TSC patients have also been reported to have either, angiomyolipomas or lipomas, the diagnosis in these cases being made via CT. We present the first case of an adult with TSC, where a histological diagnosis of cardiac lipoma was made and discuss its implications.

The pathogenesis and imaging of the tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by the formation of hamartomatous lesions in multiple organ systems. It is the second most common neurocutaneous syndrome after neurofibromatosis type 1 and has been recognized since the late 1800s. Although the disease has complete penetrance, there is also high phenotypic variability: some patients have obvious signs at birth, while others remain undiagnosed for many years. In addition to skin lesions, TSC patients develop numerous brain lesions, angiomyolipoma (AMLs), lymphangiomyomatosis (LAM) in the lungs, cardiac rhabdomyomas, skeletal lesions, and vascular anomalies, all of which are well seen with medical imaging. Our knowledge of TSC genetics and pathophysiology has expanded dramatically in recent years: two genetic loci were discovered in the 1990s and recent elucidation of TSC's interaction with the mTOR pathway has changed how we manage the disease. Meanwhile, medical imaging is playing an increasingly important role in the diagnosis, management, and treatment of TSC. We provide an update on the genetics and pathophysiology of TSC, review its clinical manifestations, and explore the breadth of imaging features in each organ system, from prenatal detection of cardiac rhabdomyomas to monitoring rapamycin therapy to treatment of AMLs by interventional radiology.