Cardiac valve papillary fibroelastomas: Clinical, histological and immunohistochemical studies and a physiopathogenic hypothesis

Background and aim of the study: Cardiac papillary fibroelastoma (CPF) is a rare and histologically benign tumor, but may have a malignant propensity for life-threatening complications; thus, surgical removal is justified. Ca se histories were reviewed of four patients who underwent surgical manageme nt after diagnosis of CPF located on aortic (n = 2) or mitral (n = 2) valve s. Our aim was to provide explanations for the clinical diversity of the le sions and, using histological and immunohistochemical methods, to hypothesi ze the genesis of these tumors. Methods: Among four patients with a diagnosis of valvular CPF, two had prev ious and recent history of neurological embolic symptoms with small echogra phically located tumors attached to the ventricular side of aortic cusps. T wo other patients (one with paroxysmal atrial fibrillation, one with no neu rological or rhythmically related stroke) had CPFs located on the posterior or anterior mitral leaflets. Results: Surgical excision was performed with a conservative valve-sparing approach. Histological and specific immunohistochemical (IHC) studies were conducted on all samples. The postoperative course was uneventful, and hist ological analysis confirmed the diagnosis of CPF with typical fronds charac terized by three successive layers. In the first two patients there was cor relation between neurological events and the presence of thrombus aggregate d on the injured superficial endothelial layer. In the other patients, no e ndothelial damage or thrombus was found. IHC studies showed dysfunction of the superficial endothelium, a centrifugal mesenchymal cellular migration a rising from the central layer to the superficial layer with differentiation steps, the presence of dendritic cells in the intermediate layer, and remn ants of cytomegalovirus (CMV) in the intermediate layer. Conclusion: Despite their benign histological aspect, and independent of th eir size, CPFs justify surgical excision because of their high potential to systemic embolization. In most cases, valve sparing management is possible with no observed recurrence after complete excision. The presence of dendr itic cells and CMV strongly suggests the possibility of a virus-induced tum or, therefore evoking the concept of a chronic form of viral endocarditis.