In July 2020, a 70-year-old woman presented with progressive dyspnea and was admitted to a local hospital. The patient had no medical history. Blood tests and electrocardiography showed no abnormalities. Transthoracic echocardiography (TTE) showed massive pericardial effusion. Chest enhanced computed tomography (CT) revealed pericardial effusion with no signs of tumors or tuberculosis. The local hospital performed 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), which showed intense FDG uptake in the pericardium (maximum standardized uptake value: 9.6), the area surrounding the left atrium, and mediastinum (Figure 1). The corresponding CT images demonstrated a mass in the pericardium (1.7 x 1.2 cm) combined with pericardial effusion and scattered soft tissue masses in the area surrounding the left atrium and mediastinum. No distant tumor sites or infiltration were detected. A pericardial window was performed via thoracoscopy, and a limited pericardiectomy was carried out. A pericardial biopsy was performed, and a pathological diagnosis of mesothelial cell hyperplasia was made at the local hospital. The patient was discharged without a definitive diagnosis and was prescribed a diuretic to alleviate her symptoms at home.
After 3 months, the patient was referred to our hospital because of worsening shortness of breath and increasing volume of the pericardial effusion. On physical examination, her respiration rate was 25 breaths/min, her pulse rate was 90 beats/min, and her blood pressure was 105/70 mmHg. Reduced breath sounds were heard in both lungs. TTE revealed a homogeneous isoechoic pericardial mass (75 x 30 mm) with massive pericardial effusion (Figure 2A). Neither ventricle was enlarged, and the left ventricular ejection fraction was estimated at 70%. The cardiac valves were morphologically and functionally normal. Contrast-enhanced ultrasonography (CEUS) was then performed with ultrasound contrast agent Sono Vue (Bracco, Italy) intravenous injection. Compared with the adjacent myocardium, the mass was hyper-enhanced (Figure 2B). Further cardiac MRI (CMRI) (Figure 3) showed a pericardial mass attached to the wall of the left atrium with invasion to the pericardium and vessels. The tumor showed irregular enhancement after gadolinium injection. The pericardial biopsy showed that the cells were positive for mesothelial cell markers (calretinin and D2-40) by immunohistochemistry (IHC), and CDKN2A (p16) deletion was detected by fluorescence in situ hybridization (FISH) (Figure 4). Finally, the patient was diagnosed with epithelioid mesothelioma of the pericardium. Given the invasion of adjacent tissues and metastasis, the cancer was deemed inoperable. The patient's dyspnea was alleviated by diuretics and drainage of the pleural effusion. Chemotherapy was not administered because the patient could not tolerate the side effects. She died nearly 2 months after the diagnosis.