Neoplasms and the Heart



Neoplasms and the Heart






SECTION 1 CLASSIFICATION OF NEOPLASMS OF THE HEART






FIGURE 9.1 Patterns of involvement of the heart and pericardium by primary and secondary tumors. (Adapted from Buja LM. Cardiac tumors. In: Willerson JT, Sanders CA, eds. Clinical Cardiology (The Science and Practice of Clinical Medicine). New York, NY: Grune & Stratton; 1977:400-404.)



  • Primary benign neoplasms of the heart



    • Atrial myxomas


    • Papillary fibroelastomas


  • Primary malignant neoplasms of the heart



    • Angiosarcoma


    • Rhabdomyosarcoma


    • Fibrosarcoma


    • Leiomyosarcoma


  • Metastatic neoplasms of the heart



    • Carcinoma


    • Sarcoma


    • Hematologic malignancies



      • Leukemia


      • Lymphoma


      • Myeloma



SECTION 2 BENIGN NEOPLASMS

Numerous types of benign neoplasms can have their origin in the heart. Myxomas and papillary fibroelastomas account for the majority of these abnormalities. Additionally and less commonly, there are lipomas, fibromas, hemangiomas, and rhabdomyomas. The incidence of these neoplasms varies from children to adults with children more commonly having rhabdomyomas and fibromas. In contrast to those in adults, these neoplasms often occur in the myocardium and either have a mass effect or are arrhythmogenic.

This section illustrates myxomas and papillary fibroelastomas. Some of these images have been used in other sections but also fit well in this section of neoplasms of the heart.


ATRIAL MYXOMA

Atrial myxoma is a benign tumor of the heart and is one of the most discussed abnormalities in cardiology. Myxomas are common topics on teaching rounds, medical conferences, textbooks, and board examinations. They have a wide variety of clinical manifestations, physical findings, and appearances on various imaging techniques. The clinical manifestations vary from fever anemia and high sedimentation rate to diastolic rumbles and “tumor plops.” The common ones are embolization and symptoms due to valve obstruction. A diastolic rumble and symptoms of exercise-induced shortness of breath as seen in mitral stenosis can be mimicked by large atrial myxomas. A diastolic rumble can be present with valve obstruction as seen in rheumatic valve stenosis, but in the case of a myxoma, a “tumor plop” is substituted for an opening snap especially when it is a left-sided tumor. Today, hearing such a sound is a rare occurrence since these tumors are often discovered earlier in the course of their natural history. “Tumor plops” are generally of a lower pitch than opening snaps.

Imaging techniques have moved the discovery of atrial myxomas earlier in their natural history. Echocardiography has played a major role in early discovery of myxoma, thus leading to resection before the dreaded embolic consequences have occurred. Computerized tomography (CT) and cardiac magnetic resonance imaging (CMRI) have also played a role in the early diagnosis of myxoma. CT scans with contrast for abnormalities such as pulmonary embolus can uncover left atrial myxomas as will be illustrated later. CMRI also has the same potential to discover these masses early in their course. Even coronary arteriography has the potential to discover an unusual coronary artery leading to a “tumor blush” with motion suggesting that is a myxoma.

Atrial myxomas have some unusual characteristics under the microscope. They contain lots of myxoid tissue and few cells. Myxomas have an endocardial lining and underneath have scarce myxoma cells that have a propensity to congregate around vascular tissue within the tumor. They have venous lake-like areas that empty into the surrounding chamber. This phenomenon can be seen in one of the following illustrations.



Large Left Atrial Myxoma on 2D and 3D Echocardiography

Determining the site of origin of the tumor is important for the surgeon. The use of 2D and 3D imaging can reveal the origin especially if the myxoma has a pedicle. Surgeons are very familiar with these sites of origin. Identification of the site of origin by imaging techniques gives the surgeon the best opportunity for complete removal.

In this example on 3D, one can see the pedicle of the myxoma tugging on the atrial septum in the region near the aorta.






FIGURE 9.2 LA myxoma demonstrated as it partially obstructs the MV orifice in diastole. Repeated pounding of the tumor on the mitral valve can cause damage—this has been called “wrecking ball effect.” M, myxoma. TEE, 114° view with color Doppler.


Myxomas on Microscopic View

Under the microscope, myxomas have a characteristic appearance. The dominant feature is the myxoid tissue that has interspersed a scant number of spindlelike myxoma cells. Additionally, there are large venous sinusoidlike vessels that exit to the chamber of origin. Around these vascular structures, the myxoma cells congregate in a halolike fashion in the perivascular region. The junction of the tumor itself and usually the adjacent atrial wall is well defined microscopically with no invasion of that adjacent tissue. The principles of removal of myxoma is to
remove the origin of the base of the tumor—that is remove the wall of the atrium from which it arose. The other principle is to carefully remove the tumor intact, thus avoiding fragmentation and subsequent embolization of myxoma tissue.

The microscopic appearance of these tumors is shown in Figure 9.3.






FIGURE 9.3 A halo of myxoma cells surrounding a vessel.


PAPILLARY FIBROELASTOMA

These benign tumors are small and usually attached to the aortic valve most commonly but sometimes attached to the mitral valve and rarely in other areas of the heart. They usually have a stalk and therefore have some mobility. Most commonly, they are single; however, as in the following example, they may be multiple. Under the microscope, they have a characteristic appearance described as a “sea anemone” in that they have hyaline material lined with endothelium. These do have embolic potential that comes to mind when these small tumors are visualized on echocardiography and have been removed surgically when this has occurred.

The following illustrations demonstrate one of these tumors at postmortem examination and one that was discovered as part of an evaluation for hypertrophic cardiomyopathy. The example of the mitral valve had embolized to the retina and was subsequently removed.1







FIGURE 9.4 An autopsy specimen that shows an incidentally found papillary fibroelastoma. It appears as a small rounded multilobulated mass attached to the edge of the aortic valve cusp on the ventricular side of the valve (black arrow).






FIGURE 9.5 Microscopic view of the above papillary fibroelastoma demonstrating mucopolysaccharide-rich material covered with endothelium. Sea anemone-like appearance.

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May 5, 2019 | Posted by in CARDIOLOGY | Comments Off on Neoplasms and the Heart
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