Case 227. Viral myocarditis (31 y-o F)
　 　 　 　 　
　 　
Autopsied heart (500 g) in case of acute cardiac failure
 　 　
　 　 　 　 　
　 　
Key words : viral myocarditis, enterovirus, giant cell myocarditis
 　 　
　 　 　
　
　 　 　
Mononuclear infiltration is evident in the edematous interstitium of the heart muscle. Coagulation necrosis of cardiomyocytes is associated (HE). 　 High powered view discloses mononuclear infiltation and necrosis of cardiomyocytes. In such a fulminant and lethal myocarditis, serologic diagnosis is actually of no use. Enterovirus (Coxsackie virus) infection is suspected.
　 　 　
　
　 　 　
Reference case 227A
Myocarditis seen in a suddenly dead 6 month-old infant. Multifocal necrosis of cardiomyocytes is observed (HE).　No owl eye inclusions are discerned in H&E preparation. This is the same patient presented as case 90 (CMV pneumonia).		 　 Reference case 227A
In situ hybridization histochemistry identifies CMV-DNA in a few cardiomyocytes.　Immunostaining for CMV antigen was also positive. When the infected cell number is small, histochemical demonstration of CMV antigen or genome may be needed, as was so in this case.
　 　 　
　
　 　 　
Reference case 227B
Giant cell myocarditis in a 23 y-o female. Marked loss of cardiomyocytes is noted (HE).　The etiology of this acute lethal condition is unknown. The cause of idiopathic myocarditis can be viral or rickettsial.		 　 Reference case 227B
The multinucleated giant cells are immunoreactive for CD68, confirming that they derived from macrophages (immunostaining). Desmin was negative.　The lesion can be distinguished from sarcoidosis, based on the lack of granulomatous reaction and the fulminant clinical course.