Myocarditis at Post-Mortem Examination: A Forensic Perspective

Abstract

Myocarditis is an uncommon cause of death but its myriad clinical presentations, young target population, diverse etiologies and potential to cause sudden unexpected death warrant its review. Myocarditis has been defined as myocardial necrosis and/or degeneration in the presence of an inflammatory infiltrate adjacent to the damaged myocytes. The type of predominant inflammatory cell present may assist with elucidating its pathoetiology. Ancillary testing as an adjunct to routine histopathological examination, such as immunohistochemical or immunofluorescence staining or detection of viral nucleic acid are of debatable diagnostic use in either the biopsy or autopsy setting. Myocarditis may clinically and/or histologically mimic other disease entities such as acute or organizing myocardial infarction, or hematological malignancy. There are no macroscopic pathognomonic features suggestive of myocarditis, thus in cases of unexplained sudden death it is vital to sample the heart extensively to rule out myocarditis. It is important to recognize that myocarditis may be an incidental finding in an autopsy. To attribute the cause of death to myocarditis, all relevant case findings including scene investigation, autopsy and ancillary testing including toxicology should be assessed.

Fatal Myocarditis Following Administration of Zoledronic Acid: A Case Report

“…Other methods such as immunohistochemical or immunofluorescence staining and viral nucleic acid studies are also done but are of debatable use. [7] Although some other reported cases had pericarditis together with myocarditis after the administration of Zoledronic acid, this case did not show the involvement of pericardium. [8] In this case, the patient was suspected to have a plasma cell neoplasm which was later confirmed by the postmortem bone marrow biopsy.…”

Histologic Examination of the Heart in the Forensic Autopsy

“…If neutrophils are the dominant cell type, bacterial and fungal etiologies must be considered, possibly resulting from conditions such as endocarditis with abscesses and/or septic emboli, sepsis, or direct extension from pneumonia. The Dallas criteria are frequently cited as diagnostic requirements for myocarditis, which requires myocyte necrosis or degenerative changes to be seen, but these criteria were developed for endomyocardial biopsies and were never intended for postmortem or post-transplant cardiac examination (9). Myocarditis is not associated with myocyte injury away from areas of inflammation, which is part of what distinguishes it from ischemia and neurocardiogenic injury (Image 12).…”

“…The myocyte injury pattern seen in postmortem cardiac sections consists of destruction of myocytes by inflammation, or patchy fibrosis associated with residual inflammation. Other authors have proposed criteria involving counting the number of lymphocytes or requiring immunohistochemical (IHC) stains for the diagnosis of myocarditis; this is of questionable practical utility in a forensic setting (9). Mixed cellular and lymphocytic myocarditis are presumably viral, although molecular and IHC testing for viruses on autopsy material is often low-yield.…”