Single-incision Subxiphoid Surgery Used for Ectopic Tumor
A minimally invasive chest surgery using a single-incision subxiphoid approach was used to effectively remove a tumor in the thymus of a 29-year-old woman with ectopic Cushing’s syndrome, as described in a recent case report.
The muscle-sparing incision causes less trauma and potentially could reduce post-surgical pain and shorten recovery time compared with traditional tumor removal procedures.
“With minimally invasive thoracic surgery under the subxiphoid approach, we have obtained an outstanding result,” the authors wrote.
The report, “Successful resolution of ectopic Cushing syndrome by minimally invasive thoracoscopic resection of the neuroendocrine tumor of the thymus: a rare case report,” was published in the journal BMC Surgery.
Cushing’s syndrome is characterized by abnormally high levels of the hormone cortisol in the blood. Cushing’s disease, a type of Cushing’s syndrome, is caused by a tumor in the brain’s pituitary gland that leads to the abnormal production of adrenocorticotropic hormone (ACTH). In turn, ACTH triggers cortisol production by the adrenal glands sitting atop the kidneys.
Ectopic Cushing’s syndrome (ECS) occurs when ACTH-producing tumors develop outside the pituitary gland in organs such as the pancreas and the lungs. They also may arise in the thyroid and thymus glands.
The thymus gland produces white blood cells, called T-cells. It has two lobes and is found behind the breastbone in between the lungs and above the heart. Traditional surgical methods of removing thymic tumors involve making a vertical incision along the breastbone to expose the heart and other organs.
In this case report, a team of researchers in China and Germany described the case of a woman with ECS caused by a thymic tumor who improved after undergoing a minimally invasive surgery.
The patient had high blood pressure and showed the classical signs of Cushing’s, including a “moon face,” a “buffalo hump,” and excessive amounts of fat around the waist. She also had excessive hair growth and acne on her face.
Lab tests indicated the patient had lower-than-normal potassium levels in the blood (hypokalemia) and a high pH in the blood (alkalosis), which led doctors to suspect hypercortisolism — excessive levels of cortisol in the body.
Further investigations showed that her morning cortisol levels were high (1,750 nanomoles per liter (nmol/L); normal range is 133–537 nmol/L)). ACTH levels also were high (57.5 picomol per liter (pg/L); normal range is  1.60–13.90 pmol/L)).
Doctors conducted a low-dose (2 mg) dexamethasone suppression test to evaluate the response of the adrenal glands to ACTH. The woman’s cortisol levels did not decline and her ACTH remained substantially high. As such, the team confirmed she had ACTH-dependent Cushing’s syndrome.
No pituitary tumor was found using a computed tomography (CT) and magnetic resonance imaging brain scans.
However, a chest CT scan revealed the presence of a thymus tumor, which was removed following a minimally invasive surgery using the subxiphoid single-incision approach. A subxiphoid incision involves making a small vertical cut below the sternocostal triangle — a nonmuscular area of the diaphragm, a large breathing muscle.
A microscopic examination confirmed the surgically-removed mass was in fact a thymic neuroendocrine tumor.
“According to our previous surgical experience, minimally invasive thoracoscopic surgery via a single subxiphoid incision has less trauma and can shorten the operation time,” the researchers wrote.
“It can also greatly reduce the postoperative pain of the patients and make the postoperative recovery faster compared with the surgical resection of the thymic tumor through [other methods],” they wrote.
One hour after surgery the patient’s cortisol levels dropped by half, and by the next day they were one-tenth of the value measured before surgery. Doctors noted ACTH levels also were significantly reduced. Her blood pressure normalized after treatment with anti-hypertensive medication.
Her recovery went well and she was discharged 10 days after surgery.
“Rapid resolution of hypercortisolemia in our case suggests that thoracoscopic resection is an effective surgical therapy for [ECS] patients. If the surgical guidelines are followed correctly, thoracoscopic surgical excision of the thymic tumor by a subxiphoid incision would be an advanced and safe surgical procedure,” the authors wrote.
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