Cardiac tumours (atrial myxoma) !

A benign, jelly-like tumour inside the heart, usually in the left atrium. It can block blood flow or shed clots and is removed by surgery.

Updated 2026-11-01

Structures involved

Tap one to see what it is and open it in 3D.

Why it happens

What it is

Primary cardiac tumours are rare; metastases to the heart are far more common. Myxoma is the most common primary cardiac tumour in adults: a soft, gelatinous, usually pedunculated mass, most often in the left atrium attached by a stalk to the interatrial septum near the fossa ovalis. Though benign, it can obstruct the mitral valve, embolise and cause systemic inflammatory symptoms.

Who gets it

Primary cardiac tumours are found in well under 0.1% of autopsies, and about half of benign primary tumours in adults are myxomas. Myxomas are most common in women between 30 and 60 years. About 7–10% are familial, most often as part of Carney complex. In children the most common primary cardiac tumour is rhabdomyoma, linked to tuberous sclerosis.

Causes

Sporadic myxoma: arises from multipotent mesenchymal cells in the endocardium, usually near the fossa ovalis
Familial myxoma in Carney complex: autosomal dominant, usually variants in PRKAR1A
Other primary tumours: papillary fibroelastoma (valves), rhabdomyoma and fibroma (children), lipoma, angiosarcoma (most common primary malignant tumour)
Secondary tumours (most common overall): metastases from lung, breast, melanoma, lymphoma and leukaemia

Risk factors

Female sex and middle age (sporadic myxoma)
Family history of myxoma or Carney complex
Tuberous sclerosis (rhabdomyoma in infants)
Advanced cancer (cardiac metastases)

Pathophysiology

Myxomas cause disease by three mechanisms. Obstruction: a mobile left atrial tumour prolapses into the mitral orifice in diastole, mimicking mitral stenosis and raising left atrial and pulmonary pressures; symptoms may change with posture. Embolism: friable fragments or overlying thrombus travel to the brain, limbs, kidneys or coronary arteries (right-sided tumours embolise to the lungs). Constitutional effects: the tumour secretes interleukin-6, causing fever, weight loss, arthralgia, anaemia and raised inflammatory markers.

Classification

Primary benign: myxoma, papillary fibroelastoma, rhabdomyoma, fibroma, lipoma
Primary malignant: sarcomas (angiosarcoma most common), primary cardiac lymphoma
Secondary: metastases by direct, lymphatic or haematogenous spread
Myxoma by location: left atrium (about 75%), right atrium, ventricles (more often in Carney complex)

Symptoms and signs

Dyspnoea, orthopnoea and pulmonary oedema (mitral obstruction)
Dizziness or syncope, sometimes positional
Sudden neurological deficit or limb ischaemia (embolism)
Fever, weight loss, fatigue and arthralgia
May be asymptomatic and found incidentally on echocardiography

Diagnosis

Clinical: Signs resembling mitral stenosis that vary with position; an early diastolic «tumour plop» after S2; constitutional symptoms. In Carney complex look for spotty skin pigmentation (lentigines), cutaneous myxomas and endocrine overactivity (Cushing syndrome, acromegaly).
Tests: Raised erythrocyte sedimentation rate and C-reactive protein, anaemia, hypergammaglobulinaemia. ECG is nonspecific. Histology after excision confirms the diagnosis; percutaneous biopsy is avoided because of embolic risk. Genetic testing and family screening when Carney complex is suspected.
Imaging: Transthoracic echocardiography is the first test; transoesophageal echocardiography defines the attachment site and size. Cardiac MRI characterises tissue and separates tumour from thrombus; CT helps plan surgery and look for metastatic disease.

Differential diagnosis

Left atrial thrombus (usually in the appendage, with atrial fibrillation or mitral stenosis)
Rheumatic mitral stenosis
Infective endocarditis with large vegetations (fever, emboli)
Other cardiac tumours, including metastases
Vasculitis or connective tissue disease (constitutional symptoms)

Goal of treatment

Remove the tumour promptly to prevent embolism, obstruction and sudden death, then follow for recurrence.

Treatment

Surgical: Prompt surgical excision on cardiopulmonary bypass, removing the stalk with a margin of the interatrial septum and repairing the defect with a patch; the valve is repaired if damaged.
Acute: Emergency management of complications while surgery is arranged: stroke or limb ischaemia pathways, treatment of pulmonary oedema; surgery is not delayed once the diagnosis is made.
Follow-up: Echocardiographic follow-up for recurrence (more frequent in familial and multiple tumours); screening of first-degree relatives in Carney complex. Nursing after surgery: rhythm monitoring for atrial arrhythmias, neurological checks and wound care.

Complications

Ischaemic stroke and other systemic emboli
Sudden death from complete obstruction of the mitral orifice
Heart failure and pulmonary hypertension
Arrhythmias
Recurrence after excision, mainly in Carney complex

Prognosis

After complete excision of a sporadic myxoma the prognosis is excellent and recurrence is uncommon. Familial myxomas recur more often and need lifelong surveillance. Malignant primary tumours and metastases have a poor prognosis.

Prevention

No primary prevention; family screening and surveillance in Carney complex
Early echocardiography in young patients with unexplained stroke or emboli

Test yourself

Think of the answer, then tap the question to see it.

Where is the classic atrial myxoma located?

In the left atrium, attached by a stalk to the interatrial septum near the fossa ovalis.

What auscultatory sound is described with a mobile myxoma?

An early diastolic «tumour plop».

Which cytokine produced by myxomas explains fever and raised inflammatory markers?

Interleukin-6.

What is the most common cardiac tumour overall?

Metastasis to the heart.

What is the most common primary cardiac tumour in children, and with which syndrome?

Rhabdomyoma, associated with tuberous sclerosis.

Add to my cards (5)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Atrial myxoma (MedlinePlus, US National Library of Medicine, 2026); Carney complex (MedlinePlus Genetics, US National Library of Medicine, 2026).

← All conditions

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.

Left atrium highlighted on the Durgical 3D model