Autopsy Specimen Collection Recommendations for Pathologic Evaluation of Myocarditis

Pathogens that cause myocarditis may be distributed focally or sparsely in the heart, despite extensive inflammatory infiltrates in the involved tissue. Because myocarditis can occur in the context of systemic diseases (e.g., Rocky Mountain spotted fever or meningococcemia), or as a manifestation of a primary infection involving another organ system (e.g., influenza), collecting multiple representative portions of cardiac tissue, as well as tissue samples from any other organ system with inflammatory cell infiltrates or other findings suggestive of infection, ensures the best chance of detecting the causative agent. Performance of specific immunohistochemical, molecular, or other assays will be determined based on the clinical and epidemiologic information provided by the submitter and the histopathologic features identified in the submitted tissue specimens.

Collection of Tissue Specimens

The preferred specimens include a minimum of 2 formalin-fixed paraffin-embedded (FFPE) tissue blocks of involved heart tissue, or representative formalin-fixed wet tissues.

Specific guidelines for these samples include:

  • Multiple fragments of cardiac tissue representing each anatomic portion of the heart involved by inflammatory infiltrates (e.g., ventricles, epicardium, pericardium, valves)

If myocarditis is identified in the context of a systemic illness, representative tissues should be included from any other organ showing significant microscopic pathology.