70-year-old woman with left atrium mass
Papillary fibroelastomas are uncommon benign tumors of the endocardium; their pathophysiology is not entirely known. They sometimes exhibit a surface lamination, consistent with the concept of growth by successive organization of fibrin deposits. The papilliferous surface is considered to result from exposure to the hemodynamic stress of flowing blood.
Papillary fibroelastoma is the most common primary tumor of the cardiac valves and the third most common primary cardiac tumor overall. Most are diagnosed between the fourth and eighth decades of life. They are slightly more common in men.
They are mostly found incidentally on echocardiography. Symptoms are usually a consequence of embolus formation.
Imaging and macroscopic findings
Echocardiographic characteristics include endocardial-based lesions with stalk attachment, high mobility, and a refractive appearance. A peripheral “shimmer,” commonly seen on a transesophageal echocardiogram, is very suggestive of the lesion. Submerging the lesion grossly in clear liquid makes fronds more apparent. They have a "sea anemone" appearance grossly.
In typical histological presentation, avascular fronds consisting of collagen and elastic fibers lined on the surface with endothelial cells are seen. The papillae are not fine or branching. A cardiac myxoma contains myxoma cells and typically lacks fine papillae. Immunohistochemically, the tumor cells express markers of endothelial differentiation, including CD31, CD34, and factor VIII, which highlight the endothelial lining. Special stains, such as Verhoeff-van Gieson elastic staining, stain elastic fibers within papillary fronds.