Multiple Intracardiac Masses: Myxoma, Thrombus or Metastasis: A Case Report

Wei-Chieh Lee; Min-Ping Huang; Morgan Fu

Disclosures

J Med Case Reports. 2015;9(179) 

In This Article

Discussion

The incidence of multiple intracavitary masses is rare. The differential diagnosis of intracavitary mass lesions includes benign, malignant primary, secondary metastatic cardiac tumors and thrombus. Because an intracardiac lesion can be detected by echocardiography, the differential diagnosis must include thrombus, vegetation and a foreign body. However, intracardiac metastases, even though rare, should also be included in the differential diagnosis, as well as infectious and nonbacterial thrombotic or marantic endocarditis.[2]

Cardiac tumors represent 0.2% of all tumors found in humans. These tumors are divided into primary or secondary/metastatic. Secondary or metastatic tumors are 20–40 times more frequent than primary tumors. Primary intracardiac tumors are rare. Approximately 75% are benign, and approximately 50% are myxomas, which have an incidence of 0.0017% in the general population.[3] Atrial myxomas are the most common (approximately 20–30%) primary intracardiac tumor in adults. Two-thirds of myxomas arise in the left atrium, whereas others arise in the RA, ventricles, SVC or pulmonary veins.[4] Only 15–20% of cardiac myxomas originate from the RA.[5] Multiple intracardiac masses are rare, and multiple intracardiac myxomas account for less than 5% of all cases.[1] The typical myxoma morphology is generally polypoid, often pedunculated, rarely sessile and round or oval, with a smooth or gently lobulated surface as observed by echocardiography.[6] RA myxomas usually originate in the fossa ovalis or the base of the interatrial septum.[7] Our case was an atypical picture of RA myxoma, as it was located in the RA lateral wall and extended to the RA auricle at the junction among the SVC and IVC. Two masses in the LV were thrombi and resolved after heparinization. The lower left lung consolidation was a suspected pulmonary thromboembolism, and also resolved after anticoagulation therapy. High levels of tumor markers, LDH and uric acid indicated a possible diagnosis of secondary malignancy.

Imaging modalities such as CT and MRI can provide additional information when echocardiography cannot delineate the extent of cardiac wall involvement. If myxoid tissue is abundantly available, the lesion will have an elevated signal in the T2WI, whereas if the fibrous component prevails, the mass will appear hypointense. Enhancement of the tumor is correlated with its histology, and the areas that are not enhanced upon imaging analysis correspond to necrosis or cystic degeneration. Enhancement is the key difference between myxomas and thrombi; the latter do not appear enhanced except in rare cases of vascularized thrombi.[8]

Myxoma surfaces may have smooth or lobulated macroscopic features. Oval, rounded, and irregular shapes have been described, and a brownish color appears to predominate. The consistency of myxomas also varies from firm to gelatinous. The microscopic features of myxomas are characterized by a myxoid matrix rich in mucopolysaccharides in which polygonal cells with an eosinophilic cytoplasm can be detected. The polygonal cells may appear as star- or nest-shaped and may be multinucleated. Microscopic characteristics including mitoses, necrosis, or pleomorphisms are usually not detected or are eventually present as mild findings.[3]

The classic triad found in patients with cardiac myxoma is characterized by obstruction of blood flow, constitutional symptoms and thromboembolic events. The obstruction of blood flow leads to intermittent heart failure, and, similar to systemic nonspecific flu-like malaise symptoms, there is usually a low fever of long duration, arthralgia, anorexia, and thromboembolic events. RA myxoma in particular can obstruct the tricuspid valve, causing signs and symptoms of right-sided heart failure, peripheral edema, ascites, hepatic congestion, and syncope. The signs and symptoms caused by myxomas are atypical and highly variable and can result in a difficult diagnosis of this neoplasia. According to the size, mobility and location of the tumor as well as physical activity and body position, patients may have an asymptomatic course or progress with thromboembolic events that may even lead to sudden death.[9,10] We share our experiences regarding RA myxomas with LV thrombi and show evidence of thrombi resolution by heparinization. Whether the intracardiac mass is benign or malignant, we still recommend surgery due to the possibilities of systemic or pulmonary massive embolism, infection, arrhythmia and sudden death if a thrombus ruptures or the mass dislodges.

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