Fibrin-associated diffuse large B-cell lymphoma is an exceptionally rare neoplasm associated with Epstein-Barr virus. It is distinguished by an indolent growth pattern within confined spaces and has a predilection for prosthetic cardiac valves, implants, and thrombi. The case is an immunocompetent 7-year-old with complex congenital heart disease and recurrent primary cardiac FA-DLBCL in association with two bovine bioprosthetic pulmonary valves. Children with complex CHD have an increased risk of lymphoma and cardiac prosthetic devices may provide environments for FA-DLBCL to occur. Pediatric oncologists must be alerted to the risk of this incredibly rare lymphoma subtype, especially among children with CHD.