Pericardial cyst

A 40-year-old man came for routine health checkup. Chest radiograph was found to be abnormal. He said he had no symptoms, and the results of a physical examination were normal. The chest radiograph (Fig 01) showed a smoothly marginated density in the region of the left cardiophrenic angle that partially obscured the left border of the heart and left dome of diaphragm. A computed tomographic scan (Fig 02) showed a homogeneous and smooth fluid attenuation lesion abutting the left ventricle. No septations or calcifications. The heart and great vessels were otherwise normal, and there was no adenopathy. Coronal and sagittal reformated images (fig03) depict the lesion better. The findings are consistent with pericardial cyst.

Pericardial cysts are an uncommon benign congenital anomaly in the middle mediastinum. They represent 6% of mediastinal masses, and 33% of mediastinal cysts. Other cysts in the mediastinum are bronchogenic – 34%, enteric – 12%, thymic and others – 21%. In the middle mediastinum 61% of presenting masses are cysts. Pericardial and bronchogenic cysts share the second most common etiology after lymphomas.

On CT scan pericardial cysts are thin-walled, sharply defined, oval homogeneous masses . Their attenuation is slightly higher than water density 30 to 40 HU. They fail to enhance with intravenous contrast. USG shows hypoechoic lesion with no calcification or septations. MRI is diagnostic, they appear hypointense on T1 and Hyperintense on T2 W images. They will not enhance on contrast study.