Case 5 -

"Borderline" PVB19 Acute Myocarditis Christina Basso, Istituto di Anatomia Patologica, Padova, Italy

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Clinical History M.A., Male 33 Year Old Circumstances of death: Italian monk was found death in his cell. Previous medical history: Asymptomatic. Healthy past medical history. No alcohol, smoke and drug addiction. No 12 lead ECG tracing was available for revision. Negative family history of sudden death (SD). Medico-legal autopsy ruled out unnatural and extracardiac causes of death. Tissues, blood and other fluids for toxicology and molecular pathology were taken before fixing the tissues and the whole heart in formalin 10%, as suggested by the European guidelines for autopsy investigation of SD (Basso et al., 2008). Gross examination of the heart: Heart weight of 360 gr, transverse diameter 10,5 cm, longitudinal diameter 9 cm. LV wall thickness 10 mm, septal thickness 12 mm, RV free wall 3 mm. Origin and course of coronary arteries are normal, with a non obstructive eccentric plaque in the left anterior descending branch. Semilunar and atrioventricular valves are normal. Histology of the myocardium (fig.2). Rare focal inflammatory infiltrates >14 cells/mm2, mostly consisting of T-lymphocyte at immunohistochemistry (CD43 and CD3 positive) were found, in the absence of clear-cut evidence of myocyte necrosis, small vessel disease, and fibro-fatty replacement (fig.1). Myofibers waviness was an additional finding. A toxicological panel was negative and drug addiction was rule out. Molecular analysis revealed the presence of parvovirus B19 (PVB19) DNA in the myocardium, whereas it was negative on extra cardiac samples (spleen and blood), thus excluding a contamination. Negative PCR/RT-PCR results were obtained for other cardiotropic virus. Legend: 1. The heart is normal at gross examination. 2-5. histological sections of the left ventricular myocardium, showing focal mononuclear infiltrates HE (2,4: x250 (3,5: x320, close –up of 2,4). Case 5 - Figure 1 Case 5 - Figure 2 Case 5 - Figure 3 Case 5 - Figure 4 Case 5 - Figure 5 Diagnosis A final diagnosis of "borderline" PVB19 acute myocarditis was put forward as possible cause of SD. Discussion Up to 20% of SD among young adults and athletes are the consequence of acute myocarditis (Basso C et al., 2001). According to the Dallas criteria for diagnosis and classification of myocarditis in endomyocardial biopsies from affected patients (Aretz HT et al., 1987), myocarditis is diagnosed by traditional hematoxylin–eosin staining in the setting of an inflammatory infiltrate of the myocardium with necrosis and/or degeneration of adjacent myocytes not typical of the ischemic damage associated with coronary artery disease. However, Dallas criteria apply strictly to endomyocardial biopsy in living patients and their sensitivity has often been questioned. Immunohistochemical techniques allow more sensitive detection and characterisation of inflammatory infiltrates (Calabrese et al, 2003). The major pending issue is the differential diagnosis between "physiologic" and "pathologic" inflammatory cell infiltrates in the myocardium (Basso et al, 2008). The presence of inflammatory cells infiltrates in the interstitium of "normal" myocardium is still a controversial issue. A cut off of five lymphocytes per high power field has been proposed for positive inflammatory cell infiltrate. The Marburg group suggested 14 cells/mm2 at immunohistochemisty as a quantitative criterion for inflammation (Maisch et al, 1995). In the case herein reported the histopathological findings are scanty and a diagnosis of "borderline myocarditis" could have been put forward. Different cardiotropic viruses have long been recognized as the most common infectious cause of myocarditis. Among the infective agents implicated, the enterovirus and adenovirus are the most frequents. More recently, several studies revealed a significant prevalence of PVB19 ranging from 2.5% to 60% (Caforio et al, 2007; Mahrholdt et al., 2006, Bock et al, 2010) also in the immunocompetent adult. However, the PVB19 was detected also in healthy transplant donors (Donoso Mantke et al., 2005), in autoptic samples without myocarditis (Schenk et al., 2009), in patients undergoing myocardial biopsy other reasons (Wang et al., 2004) or cardiac surgery for conditions not associated with viral infections (Kuethe et al, 2009), possibly as a consequence of previous infection. More recently, Stewart et al reported that, in series of adult patients with heart failure, PVB19 was associated with a wide spectrum of clinical presentation and did not support the causative role for PVB19 persistence, advocating against the use for antiviral therapy for these patients (Stewart et al 2011). Some authors suggest that PVB19 can cause myocyte damage indirectly. In situ hybridization revealed that PVB19 could infect endothelial cells of myocardial vessels, inducing endothelial dysfunction and migration of inflammatory cells into the interstitium with subsequent myocyte damage (Mahrholdt et al., 2006; Klingel et al., 2002). Alternatively, it has been proposed that myocarditis arises from immunological cross-reaction to epitopes shared between the virus and the myocardium (Murry, 2001). Since PVB19 is a frequent and common infection while myocarditis is a rare event, the involvement of other factors, both host and virus related, should be investigated to address a true causal role of the PVB19 virus. The non-availability of ECG tracing does not exclude both conduction system disease such as ventricular preexcitation and inherited ion channel disorder, such as long QT and short QT syndromes, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia, which present with well-defined abnormalities of basal or effort ECG. In this setting, the availability of ECG tracings may be crucial for the diagnosis and molecular studies are essential. Thus, although PVB19 acute focal myocarditis seems the most reasonable cause of SD in the case herein reported, due to ventricular arrhythmias, the scanty histologic features in keeping with "borderline" myocarditis and the debatable significance of PVB19 DNA in the myocardium suggest to put forward a descriptive diagnosis instead of a definitive one, accordingly to the AECVP guidelines (Basso et al., 2008). References Aretz HT, Billingham ME, Edwards WD, Factor SM, Fallon JT, Fenoglio JJ Jr, Olsen EG, Schoen FJ. Myocarditis: a histopathologic definition and classification. Am J Cardiovasc Pathol 1987;1:3-14. Basso C, Burke M, Fornes P, Gallagher PJ, de Gouveia RH, Sheppard M, Thiene G, van der Wal A; Association for European Cardiovascular Pathology. Association for European Cardiovascular Pathology. Guidelines for autopsy investigation of sudden cardiac death. Virchows Arch 2008;452:11-18. Basso C, Calabrese F, Corrado D, Thiene G. Postmortem diagnosis in sudden cardiac death victims: macroscopic, microscopic and molecular findings. Cardiovasc Res 2001;50:290-300 Bock CT, Klingel K, Kandolf R. Human parvovirus B19-associated myocarditis. N Engl J Med. 2010;362:1248-9. Caforio AL, Calabrese F, Angelini A, Tona F, Vinci A, Bottaro S, Ramondo A, Carturan E, Iliceto S, Thiene G, Daliento L. A prospective study of biopsy-proven myocarditis: prognostic relevance of clinical and aetiopathogenetic features at diagnosis. Eur Heart J 2007;28:1326-1333. Calabrese F, Thiene G. Myocarditis and inflammatory cardiomyopathy: microbiological and molecular biological aspects. Cardiovasc Res. 2003:15;60:11-25 Corcioli F, Zakrzewska K, Rinieri A, Fanci R, Innocenti M, Civinini R, De Giorgi V, Di Lollo S, Azzi A. Tissue persistence of parvovirus B19 genotypes in asymptomatic persons. J Med Virol. 2008;80:2005-11. Donoso Mantke O, Meyer R, Prösch S, Nitsche A, Leitmeyer K, Kallies R et al High prevalence of cardiotropic viruses in myocardial tissue from explanted hearts of heart transplant recipients and heart donors: a 3-year retrospective study from a German patients' pool. J Heart Lung Transplant 2005;24:1632-1638 Klingel K, Selinka HC, Sauter M, Bock CT, Szalay G, Kandorlf R. Molecular mechanisms in enterovirus and parvovirus B19 associated myocarditis and inflammatory cardiomyopathy. Eur J S 2002;4:9-12. Kuethe F, Lindner J, Matschke K, Wenzel JJ, Norja P, Ploetze K, Schaal S, Kamvissi V, Bornstein SR, Schwanebeck U, Modrow S. Prevalence of parvovirus B19 and human bocavirus DNA in the heart of patients with no evidence of dilated cardiomyopathy or myocarditis. Clin Infect Dis. 2009 Dec 1;49(11):1660-6. Mahrholdt H, Wagner A, Deluigi CC, Kispert E, Hager S, Meinhardt G, Vogelsberg H, Fritz P, Dippon J, Bock CT, Klingel K, Kandolf R, Sechtem U. Presentation, patterns of myocardial damage, and clinical course of viral myocarditis. Circulation. 2006;114:1581-90 Maisch B, Hufnagel G, Schonian U, et al, for the ESETCID investigators. The European study of epidemiology and treatment of cardiac inflammatory disease. Eur Heart J 1995;16(suppl O):173–5 Murry CE, Jerome KR, Reichenbach DD. Fatal parvovirus myocarditis in a 5-year-old girl. Hum Pathol. 2001;32:342-5 Schenk T, Enders M, Pollak S, Hahn R, Huzly D. High prevalence of human parvovirus B19 DNA in myocardial autopsy samples from subjects without myocarditis or dilative cardiomyopathy. J Clin Microbiol 2009;47:106-110. Stewart GC, Lopez-Molina J, Gottumukkala RV, Rosner GF, Anello MS, Hecht JL, Winters GL, Padera RF, Baughman KL, Lipes MA. Myocardial parvovirus b19 persistence: lack of association with clinicopathologic phenotype in adults with heart failure. Circ Heart Fail. 2011;4:71-8. Wang X, Zhang G, Liu F, Han M, Xu D, Zang Y. Prevalence of human parvovirus B19 DNA in cardiac tissues of patients with congenital heart diseases indicated by nested PCR and in situ hybridization. J Clin Virol 2004;31:20-24