Abstract and Sarcoidosis -- General Pathology
Abstract
In patients with newly diagnosed AV block and/or ventricular tachycardia, cardiac sarcoidosis should always be considered in the differential diagnosis. In addition to the pacemaker implant, cardiac resynchronization therapy (CRT) should be selected for severe heart failure patients who have class III or IV heart failure, LVEF ≤ 35%, and a complete LBBB pattern. If the disease activity is high, corticosteroid therapy is recommended. Patients with extracardiac sarcoidosis need to be closely followed for potential cardiac involvement, as the mortality in sarcoidosis depends on cardiac involvement. Early diagnosis and treatment of cardiac sarcoidosis is essential. Positron emission tomography (PET) and cardiac magnetic resonance imaging (MRI) are considered to have high sensitivity for cardiac involvement, and are the preferred imaging modalities. However, even in the era of new technology, such as PET and cardiac MRI, early diagnosis of cardiac sarcoidosis is still difficult.
Sarcoidosis -- General Pathology
Sarcoidosis is a multisystem disorder of unknown etiology characterized by the accumulation of T lymphocytes, mononuclear phagocytes, and noncaseating granulomas in involved tissue. Most frequently, the lungs are affected (90%, most commonly as bilateral hilar lymphadenopathy), and up to 30% have extrapulmonary disease, such as skin involvement (20%), ocular involvement (20%), peripheral lymphadenopathy (40%), hepatomegaly (20%), and cardiac involvement (5%). However, autopsy studies indicate that substantial subclinical cardiac involvement is present in 20% to 30% of cases. In Japanese patients with clinical sarcoidosis, it has been reported that up to 70% of patients have cardiac involvement by autopsy. In another autopsy study of 320 patients with sarcoidosis, only 43.4% of patients were known to have this disease prior to death. Death was due to sarcoidosis in 194 patients, cardiac in 150, pulmonary in 32, and of a neurological cause in 12. In patients with cardiac involvement, the diagnosis of sarcoidosis prior to death was especially low (26.7%). In those with neurological and pulmonary involvement the diagnosis was known in 50% and 59.4% prior to death, respectively.
Despite extensive research efforts, a clear etiology and pathogenesis for sarcoidosis is unknown. Antigenic stimuli such as beryllium are known to produce similar granulomas. The World Trade Center dust exposure has been reported to have an association with increased incidence of sarcoidosis. Other factors such as infection (spatial clusters of the disease might suggest person-to-person transmission, such as mycobacteria, Propionibacterium acnes, human herpes virus -8, etc.), genetic factors (HLA-A1, -B8, and DR-3 have some positive association, frequently observed in monozygotic twins), and cytokines (IL-2, -6, -8) have also been implicated as well.