A 40-year-old woman presents with positional dyspnea and a mid-diastolic murmur that changes with posture. Echocardiography reveals a left atrial mass attached to the interatrial septum. What is the most likely diagnosis?
- A Left atrial myxoma ✓
- B Left atrial thrombus
- C Papillary fibroelastoma
- D Metastatic carcinoma
Correct answer: A. Left atrial myxoma
Explanation
Left atrial myxoma is the most common primary cardiac tumor. It typically arises from the interatrial septum near the fossa ovalis and causes positional symptoms due to ball-valve obstruction of the mitral orifice. A mid-diastolic murmur that changes with posture is characteristic. Thrombus is usually associated with atrial fibrillation or mitral stenosis, not a pedunculated mass on the septum. Fibroelastomas are small and on valve leaflets. Metastases are rare and lack this classic presentation.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.