Fibrinous Pericarditis Histology and Explanation

Fibrinous pericarditis is an exudative inflammation. The visceral pericardium (epicardium) is infiltrated by the fibrinous exudate. This consists in fibrin strands and leukocytes. Fibrin describes an eosinophilic (pink) network, amorphous. Leukocytes (mainly, neutrophils) are found within the fibrin deposits and intrapericardic. Vascular congestion is also present. The myocardium has no changes. (Hematoxylin-eosine, ob. x4

A window of adherent pericardium has been opened to reveal the surface of the heart. There are thin strands of fibrinous exudate that extend from the epicardial surface to the pericarial sac. This is typical for a fibrinous pericarditis.

Microscopically, the pericardial surface here shows strands of pink fibrin extending outward. There is underlying inflammation. Eventually, the fibrin can be organized and cleared, though sometimes adhesions may remain.