A 38-year-old woman presented with chest pain. Two-dimensional echocardiography revealed a mobile mass in the left ventricle, attached to the posterior papillary muscle of the mitral valve without valvular involvement. The tumor was resected. Histopathology confirmed the tumor as papillary fibroelastoma. Our case highlights an atypical presentation of papillary fibroelastoma.

Keywords: Echocardiography, transthoracic, fibroma, heart neoplasms, magnetic resonance imaging, papillary fibroelastoma/epidemiology/pathology/surgery

After myxomas and lipomas, papillary fibroelastomas are the most common benign primary tumors of the heart (7.9%). They are also the most commonly diagnosed tumors of the heart valves.¹ These tumors are usually found on the aortic and mitral valves, and less often on the tricuspid or pulmonic valves.^1,2 The atrial endocardium is involved if the papillary fibroelastoma arises from the atrioventricular valves. If it arises from the semilunar valves, both sides of the valves can be affected.¹ Papillary fibroelastomas have been found most often on valve leaflets, chordae tendineae, and both ventricles. They are most commonly seen in men in the 5th decade of life. We present a case of papillary fibroelastoma in the left ventricle, attached to the posterior papillary muscle, in a 38-year-old woman.

In June 2004, a 38-year-old woman presented at our emergency room with chest pain and hypokalemia (3.2 mmol/L). She had no relevant medical history. During her hospitalization, a 2-dimensional transthoracic echocardiogram (TTE) showed a mobile mass in the left ventricle, attached to the posterior papillary muscle and measuring 1.9 x 1.6 cm. Cardiac magnetic resonance imaging (MRI) showed no contrast enhancement of the tumor (Fig. 1). The patient underwent surgical resection under cardiopulmonary bypass. The left atrium was entered through an incision parallel to the interatrial groove. The tumor was visible, protruding between the mitral leaflets. The leaflets themselves were not involved. Endoscopic equipment was used to determine the extent of the tumor and its attachment point, which was the apex of the posterior papillary muscle. The tumor was entwined around a single secondary chorda, without involving the mitral valve leaflets. We divided this chorda and excised the tumor. The left ventricle was reinspected for tumor, and the incisions were closed. Postoperative transesopheageal echocardiography (TEE) showed good coaptation of the mitral valve leaflets, without insufficiency. The patient had an uneventful recovery.

Pathologic Findings. Grossly, the tumor measured 2.5 x 1.5 x 1.8 cm and appeared yellowish, with polypoid and fibrotic characteristics. It was multilobular, with a sessile configuration. Light microscopy revealed a central core of dense connective tissue surrounded by a layer of hyperplastic endocardial cells, loose connective tissue, and a mesh of elastic fibers ---features consistent with papillary fibroelastoma (Fig. 2).

The origin of papillary fibroelastomas is not fully understood, but a number of mechanisms have been suggested: prior damage to the endothelium, hamartomatous origin, and organizing emboli.³ The histochemical presence of fibrin, hyaluronic acid, and laminated elastin fibers within the fronds supports the hypothesis that papillary fibroelastomas may arise from organizing thrombi.³ In a series of 12 patients,⁴ there was a strong association with previous open heart surgery or thoracic irradiation. If trauma is mechanically induced, papillary fibroelastoma can occur in proximity to the iatrogenic injury. Many of these patients⁴ had concomitant heart disease, which arouses the suspicion that repetitive hemodynamic abnormalities play a role in the pathogenesis of papillary fibroelastoma. These tumors can also occur as a delayed manifestation of radiation-induced damage in irradiated zones. Such damage has a long latency period, ranging from 9 to 31 years.⁴ In summary, most cardiac papillary fibroelastomas occur in areas of damage or stress, but many occur in normal hearts.

The histologic characteristics of the tumor consist of multiple papillary villous fronds radiating from a central fibrocollagenous stalk, with each frond showing 3 zones: a central core that contains collagen, reticulin, and elastin; a peripheral myomatous zone; and an outer rim of hyperplastic endothelial cells. It is this architecture of papillary fronds that distinguishes papillary fibroelastoma from cardiac myxoma.

Due to the introduction of TTE, more cardiac tumors are being diagnosed incidentally. There are no definitive features on TTE that distinguish papillary fibroelastoma from other intracardiac masses. Noted features include pedunculated finger-like mobile excrescences of various sizes attached to endocardial sites of intracardiac valves by a small stalk.³ The sensitiv-ity and specificity of TTE are on the order of 88.9% and 87.8%, respectively, with an overall accuracy of 88.4%, when the tumor is larger than 0.2 cm. When the tumor is less than 0.2 cm, the overall sensitivity of TTE is 61.9%, compared with 76.6% for TEE.⁵ Single papillary fibroelastomas are detected by TTE in 91.4% of cases, whereas multiple fibroelastomas are detected in 8.6%. Preoperative TEE is an important diagnostic tool that enables location of the tumor and evaluation of valvular abnormalities. Newer imaging techniques, such as contrast echocardiography perfusion imaging, may be valuable tools to better delineate cardiac masses.⁶ Small papillary fibroelastomas are difficult to see on computed tomographic imaging. Cardiac MRI appears promising. This technique gives superior visualization of cardiac tumors and of metastasis, if present.⁷

Most papillary fibroelastomas are asymptomatic. Clinical presentation varies, depending on whether the right or left side of the heart is involved. Right-sided papillary fibroelastomas are asymptomatic and rarely cause pulmonary embolism.⁸ Left-sided fibroelastomas can cause life-threatening complications. Electrocardiography, chest radiography, and blood testing are nonspecific for intracardiac masses. Elevations in erythrocyte sedimentation rate and electrolyte abnormalities, such as hypokalemia, have been observed.⁸ Patients often present with chest pain, which may be anginal or atypical. Acute myocardial infarction, caused by a tumor occluding the coronary ostium or by embolization, may be the presenting symptom.⁸ Sudden death (in younger individuals) is a rare manifestation.⁸ Cerebral embolization, either of fibrin or of a tumor fragment, has also been reported; this may present as a transient ischemic attack8 or visual disturbance. Pulmonary embolization from right-sided papillary fibroelastomas may cause respiratory distress. Multiple valvular fibroelastomas can masquerade as culture-negative endocarditis.⁸ Patients who present with clinical signs of embolization should receive anticoagulation before surgical intervention. This is especially beneficial to patients who are deemed high-risk candidates for surgery. The treatment of choice for papillary fibroelastomas is surgical excision, which is safe without causing significant morbidity or mortality. Asymptomatic left-sided papillary fibroelastomas, in particular, need elective surgical resection, because there is a higher incidence of life-threatening complications. When valvular involvement is present, excision with valve repair or replacement is curative.⁸ Our case highlights the atypical presentation of a papillary fibroelastoma attached to the posterior papillary muscle of the mitral valve, without valvular involvement. Histopathologic examination confirmed the diagnosis of papillary fibroelastoma.

Papillary fibroelastomas are benign tumors of cardiac origin that usually arise from valvular endocardium. They can cause serious morbidity and can be fatal. They are diagnosed incidentally. Most are solitary. Surgical resection is curative. Advances in cardiac MRI may provide a viable tool to differentiate benign from malignant cardiac neoplasms. Our case highlights the atypical presentation of a large papillary fibroelastoma arising from the posterior papillary muscle without valvular involvement.

The authors would like to acknowledge the assistance of Dr. Prasad Panse.