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Mass in the right atrium: an uninvited guest from the abdomen

These interesting images were shared by Dr. Ryan Henneberry, EM POCUS director at Dalhousie University.

A 47-year-old gentleman presented with shortness of breath and a focused cardiac ultrasound revealed a mass in the right atrium.

Could it be an atrial myxoma? Possible……atrial myxomas are the most common primary cardiac tumors (40-50%). But most of them are left sided with only 15–25% of cases occurring on the right side. They typically present with thromboembolic events (left) or symptoms from valvular obstruction. On POCUS, myxoma typically appears as a mobile mass attached to the endocardial surface by a stalk, usually arising from the fossa ovalis. It often appears as if it is trying to cross the mitral (or tricuspid) valve. In the above image, you do not see a clear site of origin/attachment and the mass itself is not that mobile. A thrombus is possible too, but clots are typically encountered in the background of atrial fibrillation or pulmonary embolism. Thrombi are also more common on the left, particularly occurring in the left atrial appendage.

Need to obtain more views before considering further diagnostic tests. Here is the apical 5 chamber view.

Below are the subcostal views showing the inferior vena cava and right atrium.

Now you can clearly see the mass in the IVC extending into the right atrium. CT scan revealed renal cell carcinoma (RCC) with hepatic metastases. You can actually note heterogeneous appearance of the liver in the above image (unlabeled one). So, it is not a primary cardiac tumor but an extension of the renal cancer.

RCCs are notorious for Venous migration and tumor thrombus formation. Intravascular tumor growth along the renal vein into the IVC occurs in up to 10% of all patients with RCC and further extension of the tumor reaching the right atrium is detected in ~1% of all patients. Below are two illustrative images from an open access article describing a similar case.

Here is an example of left atrial myxoma from CASE journal.

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