The Many Faces of Cardiac Sarcoidosis

Virian D. Serei, MD, PhD; Billie Fyfe, MD


Am J Clin Pathol. 2020;153(3):294-302. 

In This Article

Ancillary Studies

Sarcoidosis is a diagnosis of exclusion. It is critical to rule out other causes of granulomatous inflammation, including infectious, autoimmune, hypersensitivity, and foreign body etiologies. While the clinical context is key to determine the cause of granulomatous inflammation, special stains and immunohistochemistry are useful adjuncts. Histologically, Grocott methenamine stain and acid-fast staining aid in the detection of fungal and tuberculosis infection, respectively. In sections with poor to no granuloma formation, immunohistochemical staining for classical type 1 macrophages with CD68, type 2 macrophages with CD163, and CD209+ dendritic cells may be useful in identifying cardiac sarcoidosis.[26] A combination of decreased CD163/CD68 macrophage ratio in combination with increased CD209+ dendritic cells in nongranulomatous endomyocardial biopsies of cardiac sarcoid patients had 100% specificity for diagnosing cardiac sarcoidosis.[26]

The clinical context should also be considered, with the use of radiologic imaging studies as useful adjuncts to help diagnose probable cardiac sarcoidosis. Gadolinium-enhanced cardiac magnetic resonance imaging (MRI) can show diffuse or focal enhancement of myocardial scar tissue.[4] Positron emission tomography/computed tomography identifies active cardiac sarcoidosis through the increased uptake of fludeoxyglucose F-18 (18FDG) by activated leukocytes, macrophages, and CD4+ T cells.[4]