PMC10364123_01
The imaging feature of the cardiac mass. (A) Echocardiography revealed a large mass attached to the interatrial septum; (B) CT revealed a low-density mass within the atrium, which compressed the superior vena cava and ascending aorta.
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F1
Further evaluation by echocardiography revealed a 7.0 cm x 9.0 cm hypoechoic mass with limited motion in the right atrium, attached to the upper part of the interatrial septum with a wide base and partially protruding into the left atrium (Figure 1A). Computed tomography confirmed the presence of a massive intrapericardial mass occupying the interstitial space between the ascending aorta and the superior vena cava, which was poorly delineated from the right atrium (Figure 1B).
The surgical view of the mass. (A) A large yellow mass covering the superior vena cava and the root of the ascending aorta; (B) the mass was dissected by suspending it via surgical sutures; (C) the mass was found to originate from the interatrial septum after exposing the right atrium; (D) the right atrium was sutured.
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F2
During surgery, a large fatty tumor was discovered on the surface of the heart, almost entirely covering the right atrium and aortic root (Figure 2A). The mass was suspended for exposure of right atrium (Figure 2B). The right atrium was excised, exposing an intracardiac tumor that was attached to the atrial septum with a wide base, and infiltrated upward, penetrating the right atrial wall to form a large epicardial mass around the superior vena cava-right atrial junction and the aortic root (Figure 2C). As extensive resection was required, the defective atrium was patched using bovine pericardium (Figure 2D).The excised fatty mass was yellowish and soft, measuring approximately 7.9 cm x 8 cm (Figures 3A,B).
The macroscopical view and HE staining of resected mass. (A) Horizontal diameter of resected mass; (B) vertical diameter of resected mass; (C) HE staining result of resected mass.
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F3
As extensive resection was required, the defective atrium was patched using bovine pericardium (Figure 2D).The excised fatty mass was yellowish and soft, measuring approximately 7.9 cm x 8 cm (Figures 3A,B). Histopathological analysis of the specimen showed that the mass consisted predominantly of adipocytes (lipid droplets) with a moderate amount of fibrous tissue (Figure 3C).
The immunohistochemical staining result of resected mass. (A) The mass exhibited a positive reaction to S100 staining; (B) the mass is positive to CD34 staining.
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F4
Immunohistochemical analysis revealed that the tumor was CK(-), MDM2(-), CDK-4(-), S-100(+), CD34(+), HNB45(-), Mela-A(-), 1% ki67(1%+), focal Desmin(+), and focal SMA(-), indicating a differentiated mature lipoma with mild fibrosis (Figure 4).