Intracardiac lipomas are the second most common benign primary tumor of the heart, with varying locations. They are usually asymptomatic and diagnosed incidentally.¹ Reports of lipomas arising from the papillary muscles of the left ventricle are very rare.^1-3 To our knowledge, only two cases arising from the anterolateral papillary muscle were reported.^{1, 2}

Prestipino et al. reported a lipoma (28 x 20 mm) in the anterolateral papillary muscle in a hemodynamically stable and asymptomatic 42-year-old female, which was not resected, and showed no increase in mass dimension on follow-up MRI a year and a half from diagnosis.² Kim et al. reported a resected posteromedial papillary muscle lipoma (30 x 30 mm) in an asymptomatic 42-year-old male. The mitral valve was replaced with a mechanical prosthesis.³ Koshy et al. resected a 15 x 13 mm lipoma arising from the anterolateral papillary muscle presenting with a transient ischemic episode in a 67-year-old female with malignant melanoma. The mitral valve apparatus was left intact.¹

Biopsy may be inadequate in distinguishing between lipomas and well differentiated liposarcoma.^{4, 6} And in one report, a histopathology confirmed benign cardiac lipoma case demonstrated aggressive imaging features.⁶ Because neither imaging nor biopsy can accurately diagnose lipomatous masses, and because sudden death has been reported, surgical resection is advocated in both symptomatic and asymptomatic patients.⁴ Furthermore, early resection is suggested as cardiac lipoma patients that undergo surgical resection have good prognoses, while the prognosis for cardiac liposarcoma has a recurrence rate of approximately 40%.⁴

Our patient is young and healthy, in whom the risk of surgery is low. She refused surgery despite being apprised of the risks of conservative treatment which include overgrowth and infiltration into the myocardium with possible resultant symptoms (e.g. chest pain, valve regurgitation, arrhythmias) and concerns of embolic risk.^{2, 3, 4, 7} To our knowledge, this is the largest unresected antero-lateral papillary muscle lipoma, in an asymptomatic patient, followed up for three years since diagnosis.

Keywords Cardiac mass, Papillary muscle, Cardiac surgery, Cardiovascular risk

Financial interests: The authors have nothing to disclose.