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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.
Insights
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.
Abstract:
Several aspects of giant cell myocarditis remain controversial, including the natural history of the disease and the nature of the giant cells. We have observed three patients who had long survival with chronic active giant cell myocarditis. The first patient was a 59-yr-old female who had a 10-yr history of complete heart block which was found at autopsy to have been caused by giant cell myocarditis. The second patient is a 36-yr-old female who received a heart transplant 5 yr after a biopsy proven episode of active myocarditis, and examination of the explanted heart revealed giant cell myocarditis. The third patient was a 41-yr-old male who received a heart transplant 2 yr after developing progressive heart failure, and the explanted heart had giant cell myocarditis. On immunohistochemical study of the three hearts, the giant cells stained with the macrophage markers lysozyme and KP-1 (CD-68). Staining of the same cells with desmin and actin was focally positive in a punctate pattern, correlating with the ultrastructural presence of myofibrils within giant cell phagolysosomes. The associated lymphocytic infiltrate stained primarily for the T-cell markers CD-3, CD-45RO, and CD-43 whereas only a few of the lymphocytes stained with the B-cell marker CD-20. The long histories of cardiac dysfunction in the three patients show that giant cell myocarditis may have a protracted course. The morphologic studies show that the giant cells are of histiocytic origin but can contain phagocytosed components of myocytes, observations that may account for the controversy surrounding the nature of the giant cells in giant cell myocarditis.