Macroscopic changes of the heart are observed in severe forms of myocarditis when the dilatation of the heart chambers and changes in the myocardial consistency may occur.
The histological finding may be very various. The most common one is lymphocytic infiltrate occurring in myocarditis with viral and toxic aetiology, further in Borellia burgdorferi infection, vasculitis, and other systematic disorders [16, 38]. In bacterial myocarditis, infiltrate contains neutrophils. Eosinophilic infiltrate is characteristic for eosinophilic myocarditis, some systematic disorders (like Churg Strauss syndrome) and parasitic aetiology of myocarditis. Aschoff bodies may be observed in rheumatic fever connected with myocarditis [38]. In the case of the cardiac sarcoidosis, granulomatous infiltrate is detected [16, 38].
According to older Dallas criteria, histopathological finding in patients with myocarditis was classified in active/borderline and non-confirmed myocarditis [3]. Active myocarditis was characterized by “a distinct leukocytic infiltrate accompanied by necrosis or cardiomyocytes degeneration” and borderline myocarditis was defined by “less expressed leukocytic infiltrate.” Dallas criteria have however their imperfections [42]. It is primarily the variability in the interpretation of the results of histopathological examination of the myocardium which are influenced by the experience of the evaluating expert and by the shortage of other accompanying immunohistochemical, PCR and else examinations [42]. According to these criteria, the agent of the inflammation and its presence cannot be detected what can be important in some patients in the question of a specific, primarily immunosuppressive, therapy. Because of this reason, the use of Dallas criteria alone is not recommended and on the grounds on experts´ consensus, it is necessary to use even other methods for the evaluation of the myocardium (see chapter Endomyocardial biopsy), [42].
Authors of the opening pictures: Kurt Deb, Behrus Djavidani, Stefan Buchner, Florian Poschenrieder, Norbert Heinicke, Stefan Feuerbach, Günter Riegger and Andreas Luchner; Ed Uthman, MD; dr n. med. Krystyna Bielnik, lek. med. Dariusz Młoczkowski, dr n. med. Tadeusz Modrzewski, lek. med. Dorota Snopkowska, prof. dr hab. med. Krzysztof W. Zieliński
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References:
3) T., ARETZ a et al. Myocarditis. A histopathologic definition and classification. The American Journal of Cardiovascular Pathology [online]. 1986, 1(1), 3-14 [cit. 2017-02-06].
16) KUBÁNEK M., Kapitola 8.2.: Myokarditidy. In: KAUTZNER J., MELENOVSKÝ V., et al. Srdeční selhání – aktuality pro klinickou praxi. Praha: Mladá fronta a.s., 2015. pp. 147–157. ISBN: 978-80-204-3573-6.
38) ŠTEINER, I. Kardiopatologie: pro patology i kardiology. Praha: Galén, 2010. ISBN 978-80-7262-672-4.
42) L., BAUGHMAN. Diagnostika myokarditidy: Dallaským kritériím odzvonilo. Circulation-CZ. 2006, 5(1), 7-9.
