Teaching Case

An 81-year-old man was admitted in the emergency room for months-long, but recently aggravated, dyspnoea, asthenia, chest pain and palpitations. He had a history of recent weight loss (6 kilograms in the past three months). He was under diagnostic investigation in a different hospital for pericardial effusion.

Chest radiography showed diffuse mediastinal widening. Previous thoracic radiography from 2013 was normal.
Thoracic CT revealed heterogeneous enhanced mass occupying the entire pericardial space and surrounding the superior vena cava.

Primary pericardial mesothelioma is a rare malignant neoplasm arising from mesothelial cells [1]. It represents the most common of all primary pericardial tumours (50%), but only 0.7% of mesotheliomas [1, 2], which arise more frequently from the pleura (88.8%) and peritoneum (9.6%) [3].
Primary tumours of the pericardium can be benign (teratoma, fibroma, lipoma, angioma) or malignant (mesothelioma, sarcoma) [3, 4]. Secondary tumours are 100-1000 times more common, arising more frequently as lung, breast, melanoma or lymphoma metastasis [5].

This tumour can occur at any age, more frequently between 5th-7th decades, with a slight male predominance [2, 5].
The cause of this tumour is unknown, and unlike pleural mesothelioma, the link with asbestos exposure is unclear [3]. Factors that may play a role include radiation and recurrent serosal inflammation.
Clinical presentation is usually insidious. Common clinical manifestations are constrictive pericarditis, pericardial effusion, cardiac tamponade and heart failure [4].

Chest radiography usually demonstrates enlargement of the cardiac silhouette, an abnormal mediastinal contour, or a discrete mediastinal mass [5].
Imaging findings at CT commonly appear as pericardial effusion. Although pericardial effusion is the rule, the pericardial cavity may be obliterated by tumour, as was the case with our patient, showing an infiltrating pericardial mass that is often isoattenuating to hypoattenuating relative to myocardium. Heterogeneous enhancement after administration of intravenous contrast material is routinely demonstrated.
Computed tomography also gives details of the relationship with neighbouring structures, invasion of vital structures, and aid in the evaluation the resectability and presence of metastatic disease.
Magnetic resonance can also help in characterizing the tumour, demonstrating of myocardial invasion, and assessing the functional impact of the neoplasm on the heart [5].
Positron emission tomography (PET)/CT may be useful for evaluation of distant or loco-regional spread of disease [5].

Criteria to identify a primary pericardial mesothelioma require no tumour present outside the pericardium, with the exception of lymph node metastasis, as was also the case [2]. Lymph node biopsy confirmed the diagnosis in our patient.

Complications of pericardial mesothelioma include pericardial effusion, cardiac tamponade, compression of vascular structures or cardiac chambers, encasement of vital structures, diastolic dysfunction, constrictive pericarditis, and invasion of mediastinal structures, regional or distant metastases [5].
The prognosis is very poor due to late presentation, frequently presenting as an unresectable tumour, and weak response to radiotherapy and chemotherapy [3]. Survival after diagnosis ranges from 6 weeks to 15 months [4]. In the case of localized disease, surgical resection can be curative.