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Long survival with giant cell myocarditis
H Ren1, R S Poston, R H Hruban
1Department of General Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Summary
Giant cell myocarditis can have a prolonged course, as seen in three patients with long-term survival. Morphological studies reveal giant cells originate from macrophages and may engulf myocyte components.
Area of Science:
- Cardiology
- Immunology
- Pathology
Background:
- Giant cell myocarditis (GCM) presents diagnostic challenges regarding its natural history and the origin of giant cells.
- Understanding GCM's cellular composition and disease progression is crucial for patient management.
Observation:
- Three patients with GCM exhibited prolonged survival, with cardiac dysfunction spanning 2 to 10 years.
- One patient had a 10-year history of complete heart block attributed to GCM.
- Two patients developed progressive heart failure, leading to heart transplantation 2 and 5 years after diagnosis.
Findings:
- Immunohistochemical analysis identified giant cells expressing macrophage markers (lysozyme, CD-68).
- Focal positive staining for desmin and actin in giant cells suggests phagocytosis of myocyte components.
- The lymphocytic infiltrate was predominantly T-cell (CD-3, CD-45RO, CD-43) with few B-cells (CD-20).
Implications:
- Giant cell myocarditis may follow a protracted clinical course, contrary to some assumptions.
- Giant cells in GCM are of histiocytic origin but can contain myocyte debris, explaining previous controversies.
- These findings enhance understanding of GCM pathogenesis and clinical behavior.