Hypersensitivity Myocarditis (HM)

General: Linked to many drugs (antibiotics, anticonvulsants, antidepressants, etc.). Found in ~7% of explanted hearts, though attributed to the polypharmacy used to sustain patients until a donor heart is found.

Gross:

Microscopic: Focal infiltration of eosinophils, lymphocytes, and histiocytes in a predominantly perivascular and subendocardial distribution, with occasional focal aggregation into indistinct granulomas. Little to no myocyte necrosis.

Differential Diagnosis:

• Viral myocarditis
• AMI
• Sarcoidosis, Cardiac sarcoidosis
• Hypereosinophilic syndrome

Stains:

• Positive:
• Negative:
• Suggested, focused panel:

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Images:


Cases:

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