Rare tumor causes cyclic Cushing’s syndrome in woman, 71
Condition marked by changing cortisol levels, complicating a diagnosis
A 71-year-old woman developed cyclic Cushing’s syndrome, where periods of hypercortisolism alternate with periods of normal or low cortisol levels, as the result of a pheochromocytoma, a rare type of tumor that forms in the adrenal glands atop the kidneys.
Cushing’s syndrome is due to high cortisol levels, or hypercortisolism, often the result of a tumor that releases adrenocorticotropic hormone (ACTH), which acts on the adrenal glands to increase cortisol production. But its causes can be many.
“This case underscores the importance of considering pheochromocytoma in ACTH-dependent hypercortisolism,” the scientists wrote in their article, “A Rare Cyclic Cushing Syndrome Mystery Illustrates Diagnostic Principles,” published in JCEM Case Reports.
Tests pointed an ectopic source of ACTH, one outside the pituitary gland
Such cases can be further complicated by the difficulties in diagnosing cyclic Cushing’s syndrome, where symptoms fluctuate over time depending on cortisol levels, which can be high, normal, or too low.
“Depending on the timing of the tests relative to episodes of hypercortisolism (and their duration), test results may be normal, leading to a missed diagnosis,” wrote researchers with the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health in the U.S.
These scientists report the case of a woman with a putative diagnosis of cyclic Cushing’s syndrome, who had high blood pressure and showed common Cushing’s symptoms, such as a rounded face and weight gain around the abdomen.
She had been experiencing periods of unintentional weight gain, hair loss, skin thinning, weakness, and other symptoms — including high blood pressure, and anxiety or a sense of impending doom — in recent years. These periods alternated with episodes of nausea, weight loss, fatigue, and normal blood pressure.
ACTH-dependent cyclic Cushing’s syndrome was suspected by her doctors, but the source of ACTH was unknown. An MRI scan of the brain’s pituitary gland showed no tumor, excluding the possibility of Cushing’s disease.
Results of a diagnostic Cushing’s test called inferior petrosal sinus sampling, which measures blood levels of ACTH coming from the pituitary gland, and the response to a high dose of the corticosteroid dexamethasone, pointed to an ectopic source of ACTH, meaning a source outside the pituitary gland.
In turn, blood levels of metanephrines were about twice the upper limit of normal. Metanephrines are made when the body breaks down catecholamines, a type of hormone released in most cases of pheochromocytoma, except when the tumor is silent.
Imaging scans revealed a mass on the right adrenal gland, “suggesting a pheochromocytoma.” These results were consistent with ACTH-dependent cyclic Cushing’s syndrome.
She was prescribed medications to lower her blood pressure prior to an adrenalectomy, a surgery to remove the pheochromocytoma, which tested positive for the presence of ACTH.
After the surgery, her blood pressure normalized, and both her cortisol and ACTH levels dropped. Since the woman now produced less cortisol, she was started on replacement treatment with hydrocortisone, which was later switched to prednisone.
“Although rare, this case illustrates important management and therapeutic principles that should be considered,” the researchers wrote, adding that “timely diagnosis and treatment can reduce morbidity and improve quality of life.”
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