PMC7658372_01
Electrocardiogram reveals sinus rhythm and ST segment depression with T-wave inversion in leads V1-6.
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F1
ECG revealed ST segment depression with T-wave inversion in the precordial leads (Figure 1), which were not observed 3 years ago. A large, heterogeneous cardiac mass (30 x 39 mm, arrow) with a stalk attached to the septum was noted in the apex of the left ventricle (Figure 2A, Supplementary Video 1).
(A) Transthoracic echocardiography in apical 5-chamber view reveals an echo-dense mass (30 x 39 mm, arrow) attached to the mid-anteroseptal wall of the left ventricle, extending to the anterolateral papillary muscle. (B) Color Doppler echocardiography in apical 3-chamber view reveals a cardiac mass (arrow), and entrapment of the anterolateral papillary muscle (arrowheads), causing moderate mitral regurgitation. Ao, Aorta; LA, Left atrium; LV, Left ventricle; RV, Right ventricle.
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A large, heterogeneous cardiac mass (30 x 39 mm, arrow) with a stalk attached to the septum was noted in the apex of the left ventricle (Figure 2A, Supplementary Video 1). Color Doppler echocardiography revealed that the mass had reached the anterolateral papillary muscle (ALPM), resulting in moderate MR (Figure 2B, Supplementary Video 2).
(A) Contrast-enhanced computed tomography scan at early phase reveals an irregular cardiac mass attached to the left ventricle in several locations (arrow). (B) Note the reduced mass with a delayed contrast enhancement at late phase (arrow). (C) Axial dynamic cardiac magnetic resonance imaging reveals a low echogenic left ventricular mass attached to the anteroseptal and inferior walls, and the anterolateral papillary muscle (arrows). (D) Late gadolinium enhancement image reveals subendocardial enhancement in anteroseptal and inferior walls, mid-wall enhancement in lateral wall, and heterogeneous enhancement within the cardiac mass and the adjacent anterolateral papillary muscle (arrowheads). LA, Left atrium; LAA, Left atrial appendage; LV, Left ventricle; pm, Papillary muscle; RV, Right ventricle.
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Note an inhomogeneous and peripheral delayed enhancement as if the mass size had reduced (Figures 3A,B). Cardiac magnetic resonance (CMR) imaging further confirmed the cardiac mass, with myocardial tissue properties (Figures 3C,D).
(A-D) Photomicrograph of the resected mass. (A) Low-power view with Masson trichrome stain reveals endocardial fibrosis and intracardiac thrombosis at various stages. Note the mixed thrombus consisting of well-organized thrombus (asterisk) and fresh thrombus (double asterisk). En, Endocardium; My, Myocardium; Th, Thrombus; Bars: 1 mm. (B) A high-power view reveals proliferating neovascularization (black arrows) with inflammatory infiltrates in the border zone of endocardial fibrosis and mural thrombus (magnified view around white arrow in A). Bars: 20 mum. (C) A high-power view with hematoxylin-eosin stain reveals focal eosinophilic infiltrate in the endocardium. Bars: 20 mum. (D) Immunostaining with an antibody against the major basic protein. Bars: 20 mum.
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Pathological examination of the resected mass revealed mixed thrombus consisting of fresh, organizing, or organized thrombus, with no malignancy (Figures 4A,B). ALPM demonstrated various changes from granulation to severe fibrosis, suggesting a fibrotic stage. Although eosinophil infiltrations were observed in the endocardium, immunostaining for major basic protein, which is one of eosinophil-specific cardiotoxic granules, showed no remarkable extracellular deposition, indicating no evidence of eosinophilic activation (Figures 4C,D).
Timeline of the case. ALPM, Anterolateral papillary muscle; Ao, Aorta; Echo, Echocardiography; ECG, Electrocardiogram; En, Endocardium; LGE, Late gadolinium enhancement; LV, Left ventricle; MR, Mitral regurgitation; My, Myocardium; pm, Papillary muscle; RV, Right ventricle; Th, Thrombus. The asterisk denotes well-organized thrombus, and double asterisk denotes fresh thrombus.
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F5
As a supplement, we present a summarized illustration of the case presentation (Figure 5).