Cardiac lipoma is a rare primary benign cardiac tumor composed of mature adipose tissue, accounting for approximately 8-10% of all primary cardiac tumors. It is a well-encapsulated, round or oval, homogeneous fat-containing mass. It can develop in any cardiac location (subendocardial, subepicardial, or myocardial); most commonly seen in the left ventricle, right atrium, and interatrial septum. Diagnosis can be made with high confidence by imaging: fat density on CT (-50 to -150 HU) is pathognomonic, and T1 hyperintensity with signal loss on fat-sat sequences on MRI provides definitive diagnosis. It does not undergo malignant transformation. Surgery is not required in asymptomatic cases; resection is indicated only when hemodynamic complications (obstruction, arrhythmia) develop. Must be differentiated from lipomatous hypertrophy (of the interatrial septum) — lipomatous hypertrophy is unencapsulated and spares the fossa ovalis (dumbbell shape).
Age Range
30-70
Peak Age
50
Gender
Equal
Prevalence
Rare
Cardiac lipoma is a true neoplasm arising from mature adipocyte (fat cell) proliferation, separated from surrounding tissues by a thin fibrous capsule. The tumor shares the same histopathological features as normal subcutaneous lipomas: mature unilocular fat cells, minimal fibrous stroma, and absence of vascularity. The pathognomonic low density on CT (-50 to -150 HU) results from triglyceride molecules being composed of low atomic number carbon and hydrogen atoms — these atoms absorb very little X-radiation. The marked hyperintensity on T1-weighted MRI sequences is due to the short T1 relaxation time of fat protons — the large and slowly tumbling structure of fat molecules accelerates spin-lattice relaxation. On fat-sat sequences, frequency-selective RF pulses suppress fat protons creating signal loss — this finding provides definitive differentiation from other T1-hyperintense lesions (subacute hemorrhage, proteinaceous fluid). Absence of post-gadolinium enhancement reflects the avascular structure and homogeneous adipose tissue. Capsule integrity clearly separates the mass from surrounding myocardium and indicates absence of invasion.
Detection of homogeneous negative density values (-50 to -150 HU) in an intracardiac mass on CT. Since no tissue in the human body other than air gives negative Hounsfield values, negative density in a solid mass is definitive proof of fat content and is a pathognomonic finding that alone confirms lipoma diagnosis. This finding eliminates the need for additional imaging or biopsy (homogeneous fat density + capsule + absence of internal soft tissue component).
On non-contrast CT, a homogeneous fat density (-50 to -150 HU), well-circumscribed, encapsulated, round or oval intracardiac mass. Density measurement is identical to subcutaneous adipose tissue. The thin capsule clearly separates the mass from surrounding myocardium. No internal septation, calcification, or soft tissue component (if present, liposarcoma should be considered). This CT finding is pathognomonic and alone confirms diagnosis — additional imaging is usually not required.
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A _x_ cm homogeneous fat density (approximately _x_ HU), well-circumscribed, encapsulated intracardiac mass is seen at _location_. No internal soft tissue component or calcification is identified. Findings are consistent with cardiac lipoma.
On contrast-enhanced CT, the fat density mass shows no enhancement — density values remain identical to non-contrast examination. The thin capsule may create more conspicuous contrast with surrounding enhanced myocardium, delineating mass boundaries more clearly. Absence of enhancement confirms the avascular structure and composition of homogeneous mature adipose tissue. This finding is important for differentiation from vascularized fat-containing tumors (angiomyolipoma).
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On contrast-enhanced CT, the fat density mass shows no enhancement. The thin capsule of the mass has become more conspicuous with surrounding myocardial enhancement.
On T1-weighted sequences, lipoma shows markedly hyperintense signal — identical high signal intensity to subcutaneous adipose tissue. Signal pattern is homogeneous. This T1 hyperintensity reflects the short T1 relaxation time of fat protons. Mass boundaries are well-defined with thin capsule separating from surrounding myocardium. No internal hemorrhage, necrosis, or septation.
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On T1-weighted sequences, a markedly hyperintense, homogeneous, well-circumscribed, encapsulated mass with signal intensity equal to subcutaneous adipose tissue is seen at _location_.
On fat-saturated T1-weighted sequences, lipoma shows complete signal loss — the mass that was bright on T1 completely loses signal on fat-sat and shows lower signal than surrounding myocardium. This finding is definitive proof that T1 hyperintensity is fat-derived and confirms lipoma diagnosis. Homogeneous signal loss is important — heterogeneous signal loss or non-suppressed areas suggest presence of non-fat components (liposarcoma). Chemical shift imaging (in-phase/opposed-phase) provides similar diagnostic information: signal loss on opposed-phase creates India-ink artifact at fat-water interfaces.
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On fat-saturated T1-weighted sequences, the mass shows homogeneous complete signal loss. This finding confirms fat content and validates lipoma diagnosis.
On T2-weighted sequences, lipoma shows intermediate-to-high signal intensity (fat is also relatively bright on T2). On T2 STIR (short-tau inversion recovery) sequences, fat is suppressed showing signal loss — this provides diagnostic information equivalent to fat-sat T1. Homogeneous signal pattern is typical.
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On T2-weighted sequences, the mass shows intermediate-to-high signal. Complete signal loss consistent with fat is confirmed on STIR sequences.
On post-gadolinium sequences, lipoma shows no enhancement — definitively confirming the avascular structure of the tumor. On fat-sat post-contrast sequences (fat-suppressed contrast-enhanced T1), the mass shows low signal and absence of enhancement is most clearly evaluated on this sequence. Minimal thin linear capsular enhancement may be observed. Absence of enhancement is important for differentiating from liposarcoma (heterogeneous enhancement).
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On post-gadolinium fat-sat T1 sequences, no enhancement is identified within the mass; consistent with avascular adipose tissue.
On echocardiography, a homogeneous, hyperechoic (fat tissue is more echogenic than myocardium), well-circumscribed intracardiac mass. High reflectivity of adipose tissue creates prominent echogenicity. The capsule may be visible as a thin hypoechoic rim. Internal structure is homogeneous — no septation or calcification. Echocardiography can suggest the diagnosis but CT or MRI is required for definitive fat identification.
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Echocardiography demonstrates a _x_ cm homogeneous, hyperechoic, well-circumscribed intracardiac mass at _location_. Fat-containing lesion is suspected; CT/MRI confirmation is recommended.
Criteria
Develops below endocardium, protrudes into intracavitary space. May cause cavity obstruction and valve dysfunction. Most common in left ventricle and right atrium.
Distinct Features
Presents as intracavitary mass, risk of cavity obstruction, easier surgical access.
Criteria
Develops below epicardium, grows toward pericardium. May be confused with pericardial mass. Can cause coronary artery compression (rare). Pericardial effusion in large sizes.
Distinct Features
Extrinsic mass, growth toward pericardium, coronary artery relationship should be evaluated.
Criteria
Encapsulated fat mass in the interatrial septum. Must be differentiated from lipomatous hypertrophy: lipoma is encapsulated and involves fossa ovalis, lipomatous hypertrophy is unencapsulated and spares fossa ovalis (dumbbell shape). >2 cm favors lipoma, <2 cm favors lipomatous hypertrophy.
Distinct Features
Fossa ovalis involvement favors lipoma, sparing favors lipomatous hypertrophy. Capsule presence supports lipoma diagnosis. Arrhythmia risk (proximity to conduction system).
Distinguishing Feature
Lipomatous hypertrophy is unencapsulated, shows bilateral thickening in the interatrial septum with characteristic dumbbell shape sparing the fossa ovalis. Lipoma is encapsulated, can involve the entire septum including fossa ovalis, and is larger. Brown fat areas (mild heterogeneity) may be seen within lipomatous hypertrophy on CT and MRI.
Distinguishing Feature
Liposarcoma shows heterogeneous structure: fat areas + solid soft tissue component + septation + enhancing areas. Lipoma is homogeneous fat, encapsulated, no enhancement. On fat-sat sequences, non-suppressed solid areas are seen in liposarcoma, while complete homogeneous signal loss is seen in lipoma. Liposarcoma may have irregular borders and be invasive.
Distinguishing Feature
Teratoma has heterogeneous internal structure: fat + calcification + cystic areas + soft tissue (multiple germ layer components). Lipoma is homogeneous fat, single component. On CT, teratoma shows mixed density (negative + positive), lipoma shows homogeneous negative density. Teratoma is pediatric, more common in pericardium.
Urgency
routineManagement
surveillanceBiopsy
Not NeededFollow-up
annualCardiac lipoma is a benign tumor that does not undergo malignant transformation. Since diagnosis can be made with high confidence by imaging (fat density on CT or T1 hyperintensity + fat-sat signal loss on MRI), biopsy is not needed. No treatment is required in asymptomatic cases; annual echocardiographic follow-up is sufficient. Surgical resection indications: ventricular cavity or outflow tract obstruction, hemodynamically significant valve dysfunction, severe arrhythmias (ventricular tachycardia, AV block), and atypical features showing rapid size increase. Recurrence after surgical resection is very rare (1%). When interatrial septum lipoma is detected, differentiation from lipomatous hypertrophy should be made; size >2 cm, capsule presence, and fossa ovalis involvement are findings favoring lipoma.
Cardiac lipoma is mostly asymptomatic and discovered incidentally. Typical imaging findings (fat density, T1 hyperintensity, signal loss on fat-sat, no enhancement) are sufficient for noninvasive diagnosis, and biopsy is generally not needed. In symptomatic cases (arrhythmia, valve obstruction, compression), surgical resection is curative and recurrence is extremely rare. Conservative approach with periodic follow-up is applied for asymptomatic small lesions. In cases of heterogeneous composition, enhancing solid components, or rapid growth, liposarcoma must be excluded — biopsy is indicated in such cases.