Myocarditis is an inflammatory process affectiong the heart muscle.
Several types of inflammatory cells can be present in the heart and the type of
inflammatory cells present determines the pathologic diagnosos.

The etiology of the inflammation varies. The most common is presumed to be a
viral infection. The common viruses that affect the heart include enteroviruses
(coxsackie and echovirus), adenovirus, influenza and parvovirus B19. While other
viruses can infect the human heart they are not common causes of myocarditis.

From the pathology standpoint, the myocarditides are classified as lymphocytic,
eosinophilic, granulomatous with or with giant cells.

Endomyocardial biopsies are commonly used to establish the diagnosis of myocarditis.

Borderline myocarditis