Cardiac mass in an adult with tuberous sclerosis

Clinical History

A 59-years-old man with tuberous sclerosis and chronic renal failure was referred for further investigation, after the detection of a left ventricular mass during a routine trans-thoracic echo-cardiogram.

Imaging Findings

Cine MRI, steady-state free precession (SSFP) sequence, in short-axis and four chambers view (Fig. 1a and 1b) revealed a well-defined, small ovoid, mobile mass in the left ventricle, attached by a stalk to the endocardial surface of the mid-anterior septum; the mass was slightly hyperintense, showing a dark rim. In T2-weighted images (WI) the mass was hyperintense and with fat-saturation sequence (Short T1 Inversion Recovery - STIR), there was a complete homogeneous loss of signal intensity (SI) (Fig. 2). Left ventricular function and regional wall motion were normal. No other masses were present.

Discussion

Tuberous sclerosis (TS) is a rare neurocutaneous syndrome characterized by the presence of congenital tumours in multiple organs [1]. The estimated prevalence ranges from 1/6000 to 1/12 000 [1]. The diagnosis of TS is made clinically. Focal fatty foci in the myocardium may be found in the majority of patients with TS [2], but true intramyocardial lipomas are rare and few have been described [3]. The association of multiple intramyocardial lipomas and TS has also been reported [2].
Lipomas constitute roughly 8%–12% of all primary tumours of the heart and pericardium, the majority being extramyocardial. Subendocardial tumours are often small and sessile. As the tumour develops, various symptoms may arise, depending on his location, mobility, and size. Symptoms such as congestive heart failure, supraventricular and ventricular arrhythmia, valve obstruction, syncope, and sudden death have all been reported [4].
Imaging is often diagnostic. At ultrasound, it appears as an echogenic, well-demarcated mass. CT shows an oval mass with fat attenuation. In MRI lipomas have a homogeneous high SI on T1-WI and slightly less high SI on T2-WI, and a characteristic signal dropout on the fat-saturation sequences, confirming that it is fat-containing [5]. SSFP-Cine MRI is useful for evaluating tumour mobility (pedunculated lipomas) and rule out valve obstruction. Like soft-tissue lipomas, cardiac lipomas do not enhance after gadolinium [5].
In this case, the differential diagnosis must be made with cardiac rhabdomyoma, one of the common cardiac manifestations of TS. Rhabdomyomas usually occur before the age of 1 year, and the majority regress. Therefore, only a minority of cases present in adult life [1]. Typical findings include single or multiple masses arising in the ventricular myocardium, with a solid and homogeneous appearance, usually hypointense to myocardium on T1-WI and slightly hyperintense on T2-WI, with minimal or no enhancement with gadolinium [5].
Papillary fibroelastoma is another cardiac tumour that needs to be excluded. They typically appear as a small, round, homogeneous mass attached to valvular structures. They have intermediate SI on T1-WI and hyperintense SI on T2-WI, but they can be differentiated from lipomas in MR fat-saturation sequences as they don't show any signal dropout [5].
The majority of the patients with cardiac lipomas are asymptomatic like in this case, requiring no treatment. Surgical resection is recommended only in symptomatic patients [1].

Differential Diagnosis List

Final Diagnosis

Intraventricular lipoma

URL:	https://www.eurorad.org/case/10750
DOI:	10.1594/EURORAD/CASE.10750
ISSN:	1563-4086