10th May 2025

Diagnosis

The clinical presentation of intracavity masses is best described by Mahaim’s triad: obstruction; embolism; and constitutional symptoms. 

Obstruction

• Direct obstruction of blood flow due to mass effect, leading to syncope, especially prevalent with left atrial masses due to prolapse into the left ventricle during diastole. 
• May also cause acute congestive heart failure associated with pulmonary oedema or right ventricular heart failure.
• Valve dysfunction – either functional regurgitation or stenosis.
• If associated with atrial enlargement may lead to atrial arrhythmias such as atrial flutter or fibrillation.
• If associated with venous or ostial growth, superior or inferior vena cava syndrome may occur.

Embolism

• Due to the detachment of tumour fragments, particularly in myxomas and associated with tumour size. This may lead to any consequence of systemic emboli such as pulmonary emboli (PE), cerebral vascular accident (CVA), myocardial infarction (MI) or splenic or renal embolism.

Constitutional symptoms

• Most commonly associated with myxoma – fatigue, fever, weight loss, myalgia.
• Raynaud’s phenomenon and clubbing are associated with the release of cytokines. 

Note that cardiac masses with intramural growth (such as fibroma or cystic tumours of the atrioventricular node) frequently cause conduction disturbances and arrhythmias, including those leading to sudden cardiac death. These are much rarer and often diagnosed at autopsy and thus are much wider than necessary for this chapter.

Pericardial effusion is associated with both benign and malignant cardiac tumours, but haemorrhagic effusion is a typical manifestation of malignancies.

Additionally, some cardiac masses can be picked up incidentally at routine screening, due to being small and neither mobile nor friable.

In regards to diagnostic imaging, an echocardiogram is first line, with CMR and CT as complementary tools to further differentiate. Transthoracic echocardiogram is especially able to detect the presence of a cardiac mass but is usually limited in detecting pericardial infiltration and tissue composition. Therefore transoesophageal echocardiogram (TOE)11 is recommended for surgical assessment due to its better resolution for assessing the extent of the mass and its relationship to surrounding structures and attachments.

CMR is the best available non-invasive diagnostic tool for tissue characterisation (fibrosis, necrosis, calcification etc.) The heterogeneous tissue composition of cardiac myxomas can be visualised and appear isointense to hypointense compared with normal myocardium on T1 weighted sequences. 

CT is useful for assessing the involvement of the surrounding structures such as lung, pleural and mediastinum. Calcification is easily detectable which can be helpful in the detection of myxoma or fibroma. CMR and CT can differentiate haemorrhagic or serous pericardial effusions and can differentiate between thrombus and cardiac tumour. 

Finally, PET scan is used for staging where applicable. 

Prior to surgical intervention cytological evaluation of pericardial and/ or pleural fluid can be useful for diagnosis. However, preoperative sampling such as endomyocardial biopsy may not always be possible due to the risk of the procedure and so surgery is both diagnostic as well as part of treatment. Resected tumours are sent for histopathological analysis and some of the common features to know are as below:

• Myxoma: spindle or stellate cells, pseudovascular structure, myxoid matrix, dystrophic calcification haemorrhage 
• Sarcoma: myocardial infiltration, pleomorphism, necrosis, calcification 
• Myxoma: commonly in atria
• Sarcoma: left atrium (usually posterior wall or roof)