From Pathology Education Instructional Resource
This is a gross photograph of a heart illustrating acute fibrinous pericarditis. The pericardium on this heart has been reflected back (arrows). The surface of the heart is rough due to the deposition of fibrin on the epicardial surface of the heart and on the inner surface of the pericardium.
This is another view of the heart with the pericardium removed. Most of the epicardial surface is covered with fibrinous deposits as in the previous slide. There are a few glistening areas of exposed normal epicardial tissue.
This low-power photomicrograph illustrates the dark-red-staining fibrin deposits on the inner surface (arrows). This pericardium is much thicker than normal and there are numerous inflammatory cells within the pericardial tissue.
This is a higher-power photomicrograph demonstrating fronds of fibrin (arrows) projecting from the surface of the pericardium.
This high-power photomicrograph demonstrates fibrin (red amorphous material) on the surface of the pericardium (1). Note the reactive mesothelial cells on the surface of the pericardium (arrows) and the inflammatory cells within the pericardial tissue.