Cardiac Path Online
Pathology of Cardiac Lipoma
Cardiac lipomas are rare, benign tumours composed of adipose tissue. These tumors are usually found in adult patients but can affect patients of all ages.
Pathologists should be careful before making a firm diagnosis of cardiac lipoma since normal fat deposition in the epicardium increases with the advancing age.
Such deposition is mainly seen in the anterior surface of the ventricles, the anterior interventricular groove and along the apical course of the coronary arteries.
Excessive fat deposition is usually accompanied by fatty infiltration of the myocardium of the right ventricle and interatrial groove.
Benign lipomatous tumours of the heart include:
(i) Solitary well defined lipoma and its variant intra and intermuscular lipoma (infiltrating lipoma).
Visit: Lipoma and variants
- Multiple large lipomas encircling the whole heart and compromising all cardiac chambers is extremely rare.
- Subendocardial lipoma (large polypoid mass) with intra-cavity extension may cause valve stenosis or insufficiency.
(ii) Lipomatous hypertrophy of the atrial septum is associated with myocardial atrophy and fibrosis.This lesion usually causes cardiac arrhythmias.
(iii) Lipomatous hamartoma of atrioventricular valve involves both mitral and tricuspid valve and may involve papillary muscle. It causes valvular insufficiency.
(iv) Hibernomas of heart and pericardium have been reported.
Clinical presentation : True lipomas remain asymptomatic and are detected at routine examination. Extremely rare lipoma in children causes thickening of myocardial wall with narrowing of cardiac cavity, and are usually associated with tuberous sclerosis.
Gross appearance : Gross appearance depends on the type of lipoma:
(i) Encapsulated lipoma.
(ii) Lipomatous hypertrophy of the interatrial septum. It is usually seen as a bulge of the superior limbus, covering the fossa ovalis by the protruding atrial wall. Cut surface shows thick interatrial wall composed of yellowish-gray adipose tissue infiltrating into the adjacent atrial myocardium.
(iii) Valvular lipoma causes deformity with localized thickening, which on cut surface appear as adipose tissue.
Lipomas are defined as circumscribed encapsulated tumours.
The tumours consists of mature adipose tissue admixed with muscle cells, hence the terms myolipoma, fibrolipoma, angiolipoma etc are related to these features.
Lipomatous hypertrophy of atrial septum shows displacement and atrophy of myocardial cells by mature fat cells.
Islands of subendocardial myocytes are entrapped in the lipoma.
Occasionally, mature fat cells are intermingled with vacuolated, multiglobulat fat cells. Sometimes, granular fat cells resembling fetal fat cells may be present.
Valvular lipomas show diffuse infiltration of mature fat cells with almost complete replacement of normal tissue of the valve leaflets.
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