Primary undifferentiated high-grade pleomorphic cardiac sarcoma in the left atrium with atypical presentation

Background

Primary cardiac sarcoma (PCS) is a rare subset of soft tissue sarcomas with an approximate incidence of 0.001%–0.03%.1 The heterogeneity of symptoms, histological subtypes and response to treatment makes clinical diagnosis and management extremely challenging.

We describe a case of undifferentiated high-grade pleomorphic cardiac sarcomas (UHGPC-SRCSs) with an atypical presentation, which necessitated multimodal imaging and histological diagnosis. The involvement of multidisciplinary team (MDT) was pertinent in managing this complex case due to its poor prognosis and impracticability in ensuring a complete R0 surgical resection.2 This case also discusses the pathognomonic features and histology of sarcoma on imaging, which may help in diagnosing sarcomas.

Case presentation

A woman in her 60s presented with 4 months of malaise. She quickly developed shortness of breath on exertion, easy fatiguability and night sweats. She was deemed to have a chest infection but did not respond to a standard course of antibiotics in the community. Two months later, she noticed clubbing of her fingers and toes. She had intermittent joint swelling of her knees, hands and ankles, which resolved on an episode of night sweat. She experienced occasional palpitations but denied having chest pain, prolonged cough or haemoptysis.

At the time of presentation, the patient appeared lethargic. She had grade 3 finger and toe clubbing bilaterally (see figure 1) and mild pitting pedal oedema bilaterally. She had fine inspiratory crepitation bibasally and moderately loud pan-systolic murmur accentuated with expiration and radiated to the left axilla.

Investigations

The patient had raised C reactive protein with new onset of microcytic hypochromic anaemia. (CT) of the thorax, abdomen and pelvis demonstrated a tumour mass within the left atrium (see figure 2). Transthoracic echocardiogram (TTE) confirmed a circular dense mass attached to the left atrial septal wall with findings of severe mitral regurgitation and mild aortic regurgitation. Transoesophageal echocardiogram (TOE) showed that a broad-based mass was attached to the lower end of the interatrial septum and extended to the left atrial appendage and the floor of the left atrium (see figure 3). Multiple mobile structures were attached to the mitral leaflets. Positron emission tomography (PET) showed increased activity in the mass within the left atrium (see figure 4) and non-specific activity in some mediastinal lymph nodes, which led to an endobronchial ultrasound bronchoscopy needle aspiration. Only reactive lymphoid tissue without any malignant cells or granuloma was found. Cardiac MRI (CMRI) of the mass suggested tissue features of myxoma and intense enhancement of gadolinium ruled out lymphoma (see figure 5A–F).

A referral was made to the cardiac surgery department, and the patient was planned for a mitral valve replacement and mass resection simultaneously to obtain a histological diagnosis. The left atrial mass was polypoid with two yellow nodules measuring 30×25×10 mm and 9×10×5 mm (see figure 6). The largest nodule appeared necrotic. The tumour and mitral vegetations contained a haphazard, storiform and fascicular arrangement of predominantly spindle-shaped cells and pleomorphic bizarre cells. There were >50% of necrotic area with calcification and occasional mitoses. A mixed inflammatory infiltrate (plasma cells, neutrophils, histiocytes and occasional lymphocytes) was seen within the tumour, which stained positive for CD31 and EMA. These features (tumour differentiation 3, necrosis 3 and mitoses 1) were consistent with French grade 3 undifferentiated sarcoma.

Treatment

A biatrial septal approach was used to excise the left atrial tumour and the attached endocardium. The total bypass time was 149 min and the cross-clamp time was 128 min. Her mitral valve was replaced with a 25 mm inverted valve (Inspiris Resilia stented pericardial bioprosthesis) via the conventional median sternotomy approach after excision of the anterior leaflet and infective-looking vegetations. The mass burst intraoperatively and secreted pus-like material. The roof of the left atrium, left main artery and aorta were spared from infiltration.

No adjuvant therapy was performed immediately after the operation as the oncologist advised that it was not necessary in the event of total excision.

Outcome and follow-up

She recovered well from the operation. Once the histological diagnosis was made, she was referred to a regional sarcoma MDT for further management. The first postoperative TTE showed that the mechanical prosthetic valve was well fitted without any tumour recurrence in the left atrium. However, she started experiencing the same symptoms 2 months later while awaiting the MDT outcome and was readmitted to rule out infective endocarditis. A second TTE (see figure 7) and cMRI (see figure 8) revealed that the tumour had recurred in the same position. No distant metastasis was noted. The patient was counselled on the poor prognosis of cardiac sarcoma, and the cardiac surgery team did not think that surgery was feasible at that point. Since it was a local recurrence, the oncologist proposed 5–6 weeks of radical radiotherapy (54 Gy in 30 fractions). Her sarcoma symptoms like night sweats, fever, arthralgia and clubbing have improved since completion of radiotherapy. She had no metastatic disease, and her cardiac function was surprisingly normal.