Right Atrium Blood Cyst and Calcified Kernel in an Adult.

Among benign cardiac tumors, cardiac blood cysts are rare. These congenital lesions may develop in any heart's cavities and they are not often seen in adults. The present article is a report of a right atrium blood cyst and calcified kernel in an adult case.

Introduction

Cardiac blood cysts are exceedingly rare in adults. They are usually small, are found mainly in newborn, and mainly affect valvular apparatus. These cysts regress spontaneously in most of the patients and are very rarely detected preoperatively.

Case Report

A 73-year-old man was referred to our center for the evaluation of an incidentally detected asymptomatic cardiac mass. Physical and neurological examinations were normal. Chest X-ray and electrocardiogram were within normal limits. Hematologic studies showed no evidence of coagulation defect. Echocardiography revealed a semi mobile in homogeneous mass in right atrium (RA) about 16 × 10 mm in lower portion of interatrial septum (IAS). Other cardiac chambers were normal. Cardiac magnetic resonance imaging (MRI) showed a solitary and well-defined intracavitary RA mass about 20 × 12 × 14 mm attached to inferior and right aspect of IAS (Figure 1). In the T1 weighted-sequences with fat suppression images, the mass is inhomogeneously isosignal with no fat deposition, and in the T2 weighted-sequences, the mass is inhomogeneously high signal intensity. In the first pass perfusion sequence, the mass has no perfusion, and in the early-enhancement imaging, the mass has no perfusion, but in the late-enhancement-sequences, the mass has inhomogeneous enhancement. Coronary angiography was unremarkable. The most probable preoperative diagnosis was myxoma. Under cardiopulmonary bypass, the RA was opened. The tumor had a cystic appearance and was smooth on palpitation. During the resection, the mass was opened and was found to be a blood-filled cyst containing a calcified kernel (Figure 2A and B). The calcified kernel was a phleboliths. Histologically, the mass was a fibrous blood clot with hemosiderin pigment deposition and presence of some fibrin sclerotic nodule and calcification (Figure 3). Immunohistochemical staining of the mass was positive for cluster designation 34 (CD34), and negative for cluster keratin (CK AE1/AE3), which represents of endothelial lined cyst of the heart. The patient was discharged on the 8th postoperative day with good condition.

Figure 1.

MRI showing a solitary and round mass in the right atrium. MRI indicates magnetic resonance imaging; RA, right atrium (the arrow in the figure indicates the RA mass).

Figure 2.

(A, B) Surgical view of the blood cyst and floating white mass in the cyst.

Figure 3.

Histological image of the blood cyst.

Discussion

Cardiac blood cyst was first reported by Elasser in 1844.[1] The incidence of cardiac tumors varies between 0.001% and 0.28%.[2] The incidence of cardiac blood cyst is reportedly 0.07%.[3] Cardiac blood cysts are usually small and found in the atrioventricular valves mainly in newborn or young patients, but are extremely rare in adults. Cardiac blood cyst is often associated with a densely calcified phlebolith. The mechanism of this abnormality accompanied by calcification is still unclarified. One theory is that cysts start off as cystic nodule, then develop phleboliths due to malperfusion, and then become filled with thrombus. Cardiac blood cysts may develop in any heart cavity but we found only 4 cases located in the RA.[4-7] Blood cysts are usually asymptomatic in adult, but they can cause valvular dysfunction, embolic stroke, and pulmonary embolism. Differential diagnosis are quite challenging and consist of RA myxoma, mural thrombus, and metastatic tumor. In spite of that MRI is a powerful tool for tissue characterization of cardiac mass, because of case rarity, differentiating cardiac blood cyst from myxoma or metastases based on its results is difficult. There is no consensus regarding the optimal management of asymptomatic cardiac mass. Because of the difficulty in differentiation with other cardiac mass, surgical resection may be a suitable strategy. In conclusion, cardiac blood cysts are very rarely detected preoperatively and should be included in the differential diagnosis of cardiac masses.