Atrial Myxoma and Cardiac Tumours
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Direct answer
Atrial myxoma is the commonest primary cardiac tumour in adults, arising most often from the interatrial septum at the fossa ovalis in the left atrium. It classically produces constitutional features, obstruction of mitral flow that mimics mitral stenosis, and embolic events, with a tumour plop heard in early diastole. Echocardiography establishes the diagnosis, and complete surgical excision is curative in most patients.
What you must remember
- Site: left atrium, usually attached by a stalk to the fossa ovalis of the interatrial septum; right atrial tumours are less common.
- Constitutional features: fever, weight loss, fatigue, arthralgia, raised ESR and CRP, and polyclonal hypergammaglobulinaemia, which resolves after excision.
- Obstructive features: dyspnoea, syncope and orthopnoea from intermittent mitral inflow obstruction, mimicking mitral stenosis with a diastolic rumble.
- Tumour plop: a sharp early diastolic sound from the mass prolapsing through the mitral valve, heard best at the apex in the left lateral position.
- Embolic phenomena: stroke, retinal emboli, limb ischaemia and visceral infarction, which may be the first presentation.
- Carney complex: autosomal dominant syndrome with cardiac myxomas, skin pigmentation and endocrine tumours; familial disease recurs and needs screening of relatives.
A 48-year-old woman with breathlessness, weight loss and a stroke
A 48-year-old woman has six months of breathlessness, fatigue and weight loss, with a raised ESR and a diastolic murmur that the examiner describes as mitral stenosis-like. She then presents with a stroke, which is a recognised embolic complication, so surgery is urgent rather than elective.
- Image the mass: Transthoracic echocardiography shows a mobile, lobulated mass in the left atrium attached to the interatrial septum by a stalk.
- Refine the attachment: Transoesophageal echocardiography gives a clearer image of where the mass is attached.
- Excise the tumour: Cardiac surgeons excise it under cardiopulmonary bypass.
- Confirm on histology: The specimen shows myxoid stroma with characteristic cells.
- Check the response: Constitutional symptoms and the raised inflammatory markers usually settle after excision, which supports the diagnosis.
- Take a family history: A detailed history, including skin spots and early heart surgery in relatives, is part of the workup.
- Screen relatives: Recurrence after complete excision is uncommon but more likely in familial disease. First-degree relatives are screened with echocardiography where the family pattern suggests Carney complex.
Where the examiner tests the other cardiac tumours
Viva questions usually move from the atrial myxoma to its mimics and the other tumours. Four points recur in this area.
- Trap: Taking left atrial thrombus for myxoma. Correct: Thrombus is usually seen in the appendage and lacks a stalk attached to the septum.
- Trap: Assuming cardiac tumours are mostly primary. Correct: Cardiac metastases are more common than primary tumours and often come from melanoma, lung, breast or lymphoma, frequently with pericardial effusion.
- Trap: Missing papillary fibroelastoma as the commonest cardiac valve tumour. Correct: It is a small mobile lesion on the valve surface that causes embolic stroke and is treated by excision.
- Trap: Calling cardiac rhabdomyoma an adult tumour. Correct: It is the commonest cardiac tumour in children, typically multiple and intramyocardial, strongly associated with tuberous sclerosis and often regressing.
Lipoma is well-circumscribed and immobile, unlike the mobile myxoma.
Frequently asked questions
What is the tumour plop in atrial myxoma?
The tumour plop is an early diastolic sound caused by the myxoma prolapsing through the mitral valve during ventricular filling. It is heard at the apex and is a clinical clue to the diagnosis of atrial myxoma.
Which echocardiographic feature suggests atrial myxoma?
Atrial myxoma appears on echocardiography as a mobile, often lobulated mass attached by a stalk to the interatrial septum at the fossa ovalis. Transoesophageal echocardiography gives the clearest image when transthoracic views are inconclusive.
Which cardiac tumour is commonest in children?
Cardiac rhabdomyoma is the commonest cardiac tumour in children, and it is typically multiple and intramyocardial. It is strongly associated with tuberous sclerosis and often regresses spontaneously.
How is atrial myxoma treated?
Atrial myxoma is treated with complete surgical excision, which is usually curative and carries a low recurrence rate. Surgery is urgent when embolism or obstruction is present, because the mass can cause stroke or sudden haemodynamic collapse.