PMC5828284_01
Photomicrographies showing the main histological findings. Images A - (case 1; 10X) and B - (case 1; 20X) show cells that are interspersed within agglomerates of fibrin and present as loosely arranged clusters or glandular-like structures. Occasionally, the glandular structures show columnar cells. Image C - Histiocytes show strong cytoplasmic immunostaining for CD68 (case 1; 20X). Image D - Mesothelial cells show strong immunohistochemical positivity for calretinin. (case 1; 20X). Objective magnifications are in parenthesis after the case number.
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An incidental finding at histological examination was an agglomerate of polyhedral cells and histiocytes admixed with fibrin and erythrocytes, and focally forming strips or tubular arrays that were not attached to the valve, which appeared to correspond macroscopically to a thrombus (Figures 1A and 1B). Immunohistochemistry was positive for calretinin in some of the cells and for CD68 in others, allowing the identification of a biphasic lesion, with mesothelial cells and macrophages, respectively (Figures 1C and 1D), and the diagnosis of a mesothelial/monocytic incidental cardiac excrescence.
PMC5828284_02
Photomicrographs from cases 2 and 3. Image A - Hematoxylin and eosin (H&E) staining displays sheets and blocks of epithelioid cells within a fibrin matrix, associated with macrophages (case 2; 20X). Image B - Agglomerate of polyhedral cells and histiocytes embedded in fibrin (case 3; 20X). Image C - CD68 immunostaining shows cytoplasmic positivity in the solid cells clusters demonstrating the histiocytic nature of these cells (case 3; 20X). Image D - Calretinin immunostaining shows mesothelial cells in middle of histiocytic cells (case 3; 20X). Objective magnifications are in parenthesis after the case number.
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Additionally, and apart from the fibrotic area, an agglomerate of polyhedral cells and histiocytes were found embedded in fibrin (Figure 2B), compatible with mesothelial/monocytic incidental cardiac excrescence (Figures 2C and 2D).
PMC5828284_03
Photomicrographs from cases 2 and 3. Image A - Hematoxylin and eosin (H&E) staining displays sheets and blocks of epithelioid cells within a fibrin matrix, associated with macrophages (case 2; 20X). Image B - Agglomerate of polyhedral cells and histiocytes embedded in fibrin (case 3; 20X). Image C - CD68 immunostaining shows cytoplasmic positivity in the solid cells clusters demonstrating the histiocytic nature of these cells (case 3; 20X). Image D - Calretinin immunostaining shows mesothelial cells in middle of histiocytic cells (case 3; 20X). Objective magnifications are in parenthesis after the case number.
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Additionally, and apart from the fibrotic area, an agglomerate of polyhedral cells and histiocytes were found embedded in fibrin (Figure 2B), compatible with mesothelial/monocytic incidental cardiac excrescence (Figures 2C and 2D).