Cystic mediastinal mass

A 32-year-old woman with no other medical history presented with 1-month history of fever, weight loss and dyspnoea. On examination she had elevated jugular venous pressure and tachycardia. Her chest X-ray posterioranterior view (figure 1A) showed a rounded mass in the right cardiophrenic angle obscuring the right atrial margin, producing a 'silhouette' sign. Echocardiography showed a large cystic mass with thickened pericardium, lateral to the right atrium, causing right atrial compression (figure 1B). CT image of the chest showed a cystic lesion compressing the right atrium with thickened pericardium (figure 2A). There were no other lesions found in the lungs or other organs. Laboratory tests showed elevated erythrocyte sedimentation rate (ESR: 96 mm/hour) and C reactive protein (CRP: 32 mg/L). Excision of the mass with partial pericardiectomy was done. Intraoperatively, there was a cyst with thickened pericardial wall and thick yellowish brown fluid. Histopathology of the tissue is shown in figure 2B.Figure 1(A) Chest X-ray posterioranterior view showing a rounded mass in the right cardiophrenic angle. (B) Transthoracic echocardiography apical four-chamber view showing the cystic mass.Figure 2(A) CT of the chest sagittal view showing cystic lesion compressing the right atrium with thickened pericardium. (B) Histopathology specimen of the pericardial tissue.

What is the diagnosis and what should be the management strategy?Congenital pericardial cyst and no further evaluation required.Features are suggestive of tuberculous pericardial cyst and needs treatment with antituberculosis regimen.Features suggestive of pericardial hydatid cyst and requires treatment with albendazole.Features are suggestive of viral pericarditis with encysted effusion.