Undergraduate medical students

1. Myocarditis
Dr. Usman Shams

2. Causes
• Chiefly MICROBIAL
 COXACKIEA & B, CMV, HIV
 Trypanosoma cruzi (Chagas dis., 80%)
 Trichinosis
 Toxoplasmosis
 Lyme disease (5%)
 Diphtheria
• IMMUNE:
 Post-viral
 Rheumatic fever
 SLE
 Drug hypersensitivity (alpha-methyl
dopa, sulfas)
 Transplant
• UNKNOWN:
 Post-viral
 Giant cell myocarditis

3. LYMPHOCYTIC INFILTRATES are the USUAL pattern of ALL myocarditis, but
eosinophils, giant cells, and even trypanosomes can be seen occasionally

4. Lymphocytic
Myocarditis,
with
mononuclear
inflammatory
cell infiltrate
and associated
myocyte injury.

5. Hypersensitivity
myocarditis,
characterized by
interstitial
inflammatory
infiltrate
composed largely
of eosinophils
and mononuclear
inflammatory
cells,
predominantly
localized to the
perivascular and
large interstitial
spaces.

6. Giant cell
Myocarditis,
with
mononuclear
inflammatory
infiltrate
containing
lymphocytes
and
macrophages,
extensive loss
of muscle, and
multinucleated
giant cells.

7. Myocarditis of
Chagas
disease.A
myofiber is
distended with
trypnosomes
(arrow).There
is a
surrounding
inflammatory
reaction and
individual
myofiber
necrosis.