PMC3560259_01
Chest computed tomography (CT). (a) A 77-year-old man presented with an intrapericardial mass. Contrast-enhanced CT demonstrated a huge mass adhered to the left atrial appendage. The mass was not uniform; it lacked calcification and showed non-homogeneous enhancement (arrowheads). (b) Coronal contrast-enhanced CT shows that the mass was covered with pericardium (arrows).
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F1
The mass measured 9 x 6 x 4 cm (Figure 1a, 1b). 
Magnetic resonance imaging. (a) A T1-weighted image (T1WI) demonstrated a well-defined mass of slightly high intensity. (b) A T2WI demonstrated a mixture of high- and low-intensity areas. A low-intensity septum and a peripheral rim were observed in the mass on both T1WI and T2WI.
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F2
On magnetic resonance imaging (MRI), a T1-weighted image (T1WI) demonstrated a well-defined mass of slightly high intensity (Figure 2a). A T2-weighted image (T2WI) demonstrated a mixture of high- and low-intensity areas (Figure 2b).
Fused positron-emission tomography (PET) and computed tomography (CT) image. (a) Axial fused PET and CT image shows 2-[18 F] fluoro-2-deoxy-d-glucose (FDG) uptake in the peripheral rim of the mass (arrowheads). The maximum standardized uptake value (SUV) of this lesion was 3.50. (b) Coronal fused PET and CT image. Other signs of abnormal uptake suggesting a malignant lesion were not observed in other intrapericardial mass (arrowheads).
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F3
FDG-PET images revealed uptake in the peripheral rim of the mass (Figure 3a, 3b).
Macroscopic and pathological findings. (a) Macroscopic observations showed that the resected mass consisted of a dark red, partially organized hematoma containing a small amount of liquid with a fibrous membrane. (b) Pathological examination showed a hematoma surrounded by dense fibrous tissues, and the center of the hematoma consisted of fresh and old hemorrhages. Focal infiltration of hemosiderin-laden macrophages was observed in the outer zone of the peripheral wall. No malignant change was observed.
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F4
Macroscopic observations showed that the resected mass consisted of a dark red, partially organized hematoma containing a small amount of liquid with a fibrous membrane (Figure 4a). No malignant change was observed (Figure 4b).