Woman’s Repeat MG Flares Likely Due to Rare, Benign Heart Tumors

Patricia Inacio, PhD avatar

by Patricia Inacio, PhD |

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A woman with repeat myasthenia gravis (MG) flares was found to have several rare and benign tumors in her heart, a case study reported.

According to its scientists, this case highlights the importance of cardiac evaluations of MG patients, particularly those with recurring episodes of myasthenia gravis exacerbation, or periods of disease worsening.

The report, “Myxomatous tumours of the right atrium in a patient with recurring myasthenia gravis exacerbations,” was published in the journal BMJ Case Reports.

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The woman, in her 50s, had been diagnosed with MG in 2020 after experiencing generalized muscle weakness and visual problems. She had tested positive for self-reactive antibodies against acetylcholine receptors (AChR), the most common type of autoantibodies seen in MG patients.

Four days before arriving at Albany Medical Center Hospital in New York, her symptoms again worsened; doctors noted she had three hospitalizations in the previous six months. Upon admission, her vital signs were stable and a physical exam was unremarkable, noting only drooping of the upper eyelids or bilateral ptosis.

She underwent plasma exchange, a treatment that involves replacing a person’s plasma — the non-cellular part of blood — to help eliminate MG-causing antibodies circulating in the bloodstream.

A chest CT scan showed no signs of a thymoma, a rare tumor in the thymus gland that is found in up to 15% of all MG patients.

However, the imaging test showed the presence of a mass in the heart’s right atrium, the chamber that receives oxygen-poor blood returning from across the body. This mass, known as a myxoma or rare and benign heart tumor, was confirmed in a subsequent imaging test called a transthoracic echocardiogram or TTE.

The patient’s heart function was not compromised. She completed two rounds of plasma exchange therapy, with subsequent improvement in her vision and a lessening of muscle weakness.

At this point, the woman agreed to surgery to remove the myxoma along with the thymus — a procedure called a thymectomy —  to lower the risk of another myasthenia gravis exacerbation.

Several myxomas were found and removed during the surgery, one large tumor that measured 1 cm × 1.5 cm and three smaller ones measuring 3–5 mm. The entire surgery, including the thymectomy, concluded without complications.

Later tissue analysis showed the cardiac masses to be consistent with myxomas and the thymus to be enlarged, a condition known as thymus hyperplasia.

The woman was soon discharged to a rehabilitation center to recover muscle strength. Monthly follow-ups, ongoing for six months at the time of this report, showed she remained stable.

This “case is unique in that we describe [right atrium] myxomas in a patient with recurring MG exacerbation,” the scientists wrote, noting myxomas are primarily found in the heart’s left atrium.

“We propose that patients with diagnosis of MG may benefit from a cardiac workup (TTE) and that dual procedures (myxoma resection and thymectomy) may be successful in subsiding recurring MG exacerbations,” they added.