Cardiac Path Online

Pathology of Cardiac Myxoma

Dr Sampurna Roy MD

 

                                                                                                                      

 

Myxomas are the most common primary cardiac tumours.

 

A left atrial myxoma was first described in 1845. 

 

Myxomas are neoplasms of endocardial origin.

 

The tumour usually projects from the endocardium into the cardiac chamber. 

Histogenesis:

Cardiac myxomas originate from primitive, multipotential, mesenchymal cells, present in the heart-wall as embryonic remnants.

Immunohistochemical study supports this concept.

It also suggests that myxoma cells are derived from primitive subendocardial cells (not endothelial origin).

Some myxomas contain stellate cells resembling Schwann cells and cells with positive neuroendocrine markers, suggesting the view that myxomas originate from endocardial sensory nerve tissue.

Myxomas with gland like spaces contain mucus-secreting cells.

Immunohistochemical studies suggest that myxomas originate from cells having potential for both epithelial and mesenchymal differentiation.

On this basis myxomas are considered as hamartomas.

This is also supported by the study of proliferative and metastatic potential and expression of oncogene/tumor suppressor gene products.

Age and sex:  

Myxomas occur in all age groups but are particularly frequent between the third and sixth decades of life.

Women predominate in most series.  

Clinical presentation: 

Embolism occurs in a number of patients with myxomas.

Systemic embolism is particularly common as  most myxomas are located in the left atrium.

The vessels affected include cerebral arteries, retinal arteries (transient or permanent visual loss may result) and in some cases renal, and coronary arteries.

Complete obstruction of the abdominal aorta and renal arteries by a large tumor embolus originating from the left ventricle  and aortic saddle embolism have even been reported. 

The differential diagnosis of peripheral embolism should therefore include myxoma.

After surgical removal of the embolus, the diagnosis can often be made by histologic examination.

Myxomas commonly give rise to signs of obstructed filling of the left or right ventricle with subsequent dyspnea, recurrent pulmonary edema, and right heart failure.

Constitutional disturbances, such as fatigue, fever, erythematous rash, arthralgia, myalgia, and weight loss, and laboratory abnormalities, such as anemia and elevations in the erythrocyte sedimentation  rate and the serum C-reactive protein and globulin levels, have been observed in many patients.

Site:  

Cardiac myxomas usually develop in the atria. About 75 percent originate in the left atrium, and 15 to 20 percent in the right atrium. 

Most tumours (90%) arise in the atrial septum in the region of fossa ovale, but they can also originate, in descending order of frequency, from the posterior atrial wall, the anterior atrial wall, and the atrial appendage.

Ventricular location is rare.

There have also been reports of combined atrial and ventricular tumours and biventricular tumours.

Myxomas of the heart valves are rare.

Myxomas usually occur sporadically, but familial myxomas have been reported.

Multiple myxomas are uncommon but multiple lesions in more than one cardiac chamber may occur in familial myxoma.