Ultrastructural aspect of myocarditis: its relevance for the diagnosis

Area of Science:

• Cardiovascular Pathology
• Immunohistochemistry
• Microscopy Techniques

Background:

• Myocarditis diagnosis relies on identifying myocardial inflammation.
• Distinguishing active, healing, or latent myocarditis is crucial for patient management.
• Light microscopy (LM) and electron microscopy (EM) offer different resolutions for assessing inflammatory processes.

Purpose of the Study:

• To evaluate the combined utility of LM and EM in diagnosing myocarditis.
• To correlate LM findings with EM-defined patterns of lymphocyte-cardiocyte interaction.
• To clarify discrepancies between LM and EM in staging myocarditis.

Main Methods:

• Utilized the Dallas consensus criteria for LM analysis of inflammatory loci.
• Employed EM to observe lymphocyte-cardiocyte interactions, defining deleterious and dormant patterns.
• Correlated LM observations (active, borderline) with EM patterns (deleterious, dormant).

Main Results:

• The deleterious pattern (EM) often correlated with active LM findings.
• LM's borderline appearance could correspond to either deleterious (EM) or dormant (EM) patterns.
• Discrepancies arose from LM's limited resolution, potentially obscuring disease stage.
• Combined LM and EM improved myocarditis diagnosis accuracy.

Conclusions:

• Myocarditis diagnosis requires integrated LM and EM findings.
• Active LM findings with a deleterious EM pattern indicate active myocarditis.
• Borderline LM findings require EM to differentiate healing/latent phases based on hemodynamic status.