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Cardiac Tumors: Myxoma vs Mets

TL;DR

Cardiac Tumors: Myxoma vs. Mets is a high-yield MRCP Part 1 topic focused on distinguishing primary benign tumours (especially atrial myxoma) from secondary metastatic involvement. Myxomas classically present with obstructive, embolic, and constitutional features, while metastases often manifest via pericardial disease in patients with known malignancy. Echocardiography is key for diagnosis. Recognising these patterns is crucial for exam success.


Why this matters

In MRCP Part 1, cardiac tumours are tested not because they are common in clinical practice, but because they demand pattern recognition and integration of clinical clues. Atrial myxoma is the most common primary cardiac tumour, whereas metastatic disease is far more prevalent overall.

Candidates are often asked to differentiate between these two entities using subtle features such as positional symptoms, embolic phenomena, or the presence of malignancy. For a structured revision pathway, see our MRCP Part 1 overview.


Core sections

1. Classification: Primary vs Secondary

Cardiac tumours are broadly divided into:

  • Primary tumours (rare):

    • Atrial myxoma (most common)

    • Papillary fibroelastoma

    • Rhabdomyoma (paediatric)

  • Secondary tumours (common):

    • Lung carcinoma

    • Breast carcinoma

    • Melanoma (highest cardiac spread rate)

    • Lymphoma

Exam insight: Secondary tumours are approximately 20–40 times more common than primary cardiac tumours.

2. Atrial Myxoma: High-yield features

Atrial myxoma is the most important tumour for MRCP Part 1.

Key features:

  • Typically arises in the left atrium, attached to the interatrial septum (fossa ovalis)

  • Pedunculated and mobile

  • Can intermittently obstruct the mitral valve

Classic triad:

  1. Obstructive symptoms – dyspnoea, syncope, orthopnoea

  2. Embolic events – stroke, limb ischaemia

  3. Constitutional symptoms – fever, weight loss, raised ESR

Exam pearl: A “tumour plop” is an early diastolic sound that varies with position.

3. Cardiac Metastases: Key concepts

Metastatic involvement of the heart is far more common but often under-recognised.

Routes of spread:

  • Direct extension (e.g. lung, breast)

  • Haematogenous (e.g. melanoma)

  • Lymphatic spread

Common sites:

  • Pericardium (most common) → effusion

  • Myocardium

  • Endocardium (rare)

Clinical features:

  • Known malignancy

  • Pericardial effusion ± tamponade

  • Arrhythmias or heart failure

4. Comparison Table (Exam Favourite)

Feature

Myxoma

Metastases

Frequency

Rare (primary)

Common (secondary)

Location

Left atrium

Pericardium > myocardium

Morphology

Pedunculated, mobile

Infiltrative

Symptoms

Triad (obstructive + embolic + constitutional)

Malignancy-related, effusion

Echo findings

Mobile septal mass

Effusion/infiltration

Treatment

Surgical excision

Treat underlying malignancy

5. Investigations

  • Echocardiography (TTE/TOE): first-line and often diagnostic

  • Cardiac MRI/CT: further anatomical detail

  • Blood tests:

    • Myxoma → raised ESR, anaemia

    • Metastases → tumour-specific markers

Authoritative overview:

6. 10 High-Yield Exam Points

  1. Myxoma is the most common primary cardiac tumour

  2. Metastases are the most common overall

  3. Myxoma arises from the fossa ovalis

  4. Symptoms may be positional

  5. Stroke in young → consider myxoma

  6. Constitutional symptoms mimic infection

  7. “Tumour plop” is characteristic

  8. Metastases commonly cause pericardial effusion

  9. Melanoma has the highest cardiac spread rate

  10. Echocardiography is the investigation of choice

7. Most Tested Subtopics

  • Atrial myxoma clinical triad

  • Tumour plop vs mitral stenosis murmur

  • Causes of embolic stroke in young patients

  • Malignancy-related pericardial effusion

  • Echocardiographic differentiation


Practical examples / mini-cases

MCQ:A 45-year-old woman presents with episodic dyspnoea and syncope. Symptoms worsen when she leans forward. She has lost weight and has a raised ESR. On auscultation, an early diastolic sound is heard.

What is the most likely diagnosis? A. Mitral stenosisB. Atrial myxomaC. Infective endocarditisD. Dilated cardiomyopathy

Answer: B. Atrial myxoma

Explanation:

  • Positional symptoms + constitutional features + embolic risk

  • Classic triad strongly suggests myxoma

  • Tumour plop differentiates it from valvular disease


Common pitfalls (5 bullets)

  • Mistaking myxoma for mitral stenosis

  • Overlooking embolic stroke as a presentation

  • Assuming metastases form discrete masses

  • Ignoring systemic symptoms (fever, weight loss)

  • Forgetting melanoma’s high metastatic potential

Focused late-night study session for MRCP Part 1 revision

FAQs

1. What is the most common primary cardiac tumour?

Atrial myxoma. It usually arises in the left atrium and presents with obstructive or embolic features.

2. What is the most common cardiac tumour overall?

Metastatic tumours, particularly from lung, breast, and melanoma.

3. What investigation confirms cardiac tumours?

Echocardiography is first-line and typically diagnostic.

4. What is a tumour plop?

An early diastolic sound caused by a mobile atrial myxoma, often varying with posture.

5. Why do metastases cause pericardial effusion?

They commonly involve the pericardium via lymphatic or direct spread, leading to fluid accumulation.


Ready to start?

Strengthen your revision with targeted practice using our Free MRCP MCQs or simulate real exam conditions with a Start a mock test. For structured teaching, explore our lecture series at https://www.crackmedicine.co.uk/lectures/.


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