For eight years, a 41-year-old woman kept gaining weight, felt exhausted, and developed type 2 diabetes and high blood pressure. When doctors finally traced her illness to Cushing's syndrome, the hormone-making tumor behind it turned up somewhere few would think to look: inside her right maxillary sinus, the air-filled cavity in the cheek beside the nose.
The tumor was made of pituitary tissue, the kind normally found in the pea-sized gland at the base of the brain. A team of endocrinologists, ear, nose, and throat surgeons, and a pathologist from two Bristol, England, hospital trusts described the case in a report in the Turkish Archives of Otorhinolaryngology, published Sept. 30, 2026. The authors wrote that, to their knowledge, "only a small number of ectopic pituitary adenomas located in the maxillary sinus have been reported."
What makes the case especially striking is that a scan of her pituitary gland first pointed doctors in the wrong direction.
A Pituitary Scan That Pointed the Wrong Way
Cushing's syndrome is caused by long-term exposure to too much cortisol, a hormone made by the adrenal glands, according to MedlinePlus. It is rare, affecting roughly 40 to 70 people per million, and it affects about three times as many women as men, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
The most common cause is long-term, high-dose use of steroid medicines. When those drugs are not involved, pituitary tumors are by far the usual culprit, accounting for about 8 in 10 cases, NIDDK says. These tumors pump out ACTH, a hormone that signals the adrenal glands to make cortisol.
The woman in the Bristol report had the classic picture. Doctors noted a flushed face, obesity, a fatty pad at the back of the neck, weakness in the large muscles near the hips and shoulders, and excess hair growth. Blood tests showed that her ACTH was not suppressed, meaning her cortisol excess was being driven by an ACTH source somewhere in the body.
A contrast MRI of her pituitary gland then showed a "possible right-sided microadenoma," a small spot that looked like the obvious answer. But a hormone stimulation test gave indeterminate results for a pituitary source, so the team kept digging.
Blood Sampling Near the Brain Changed the Diagnosis
The next step was inferior petrosal sinus sampling, a procedure in which thin tubes are threaded into veins that drain the pituitary gland. ACTH levels there are compared with levels in the rest of the bloodstream. NIDDK describes the test as often the best way to tell a pituitary source of Cushing's syndrome from one elsewhere in the body.
In this patient, the sampling favored a source outside the pituitary. That made the spot on the MRI an unlikely cause and sent doctors searching the rest of the body.
A CT scan of her neck, chest, abdomen, and pelvis came back unremarkable. A whole-body FDG-PET scan, which highlights metabolically active tissue, finally lit up a 12-millimeter lesion in the right maxillary sinus. The scan showed no tracer uptake in the brain or pituitary gland.
The misleading MRI finding is not that surprising. Small, unexpected pituitary spots turn up regularly on imaging. A 2025 review in Endocrinology and Metabolism put the pooled prevalence of incidental pituitary lesions at about 3.4% in MRI studies and 10.7% in autopsy studies. The Bristol authors stressed keeping a broad list of possibilities when imaging and blood tests disagree, "even when an apparent sellar lesion is present."
Pituitary Tissue Far From the Pituitary
So how does pituitary tissue end up in a cheek sinus? The front part of the pituitary forms during fetal development from a pouch of tissue called Rathke's pouch, which migrates along the midline of the head. Ectopic pituitary tumors, meaning those found outside their usual location, arise from leftover remnants of that tissue, the authors explained.
Most of these misplaced tumors therefore appear in midline spots. The report cites a review of 180 patients in which the most common sites were the sphenoid sinus, deep behind the nose (34.4%); the region just above the pituitary (25.6%); the clivus, a bone at the base of the skull (15.6%); the cavernous sinus (13.3%); and the nasopharynx (5.6%).
The maxillary sinus sits off to the side, "lying well off this midline migratory route," the authors wrote. That makes this tumor unusual even among ectopic pituitary tumors, which are themselves exceedingly rare.
Surgeons removed the growth through the nose using an endoscopic technique called a prelacrimal approach. Under the microscope, pathologists found pituitary tumor cells infiltrating the lining of the sinus. The cells stained strongly for ACTH and other markers, including TPIT, a protein found in ACTH-making pituitary cells, confirming an ACTH-producing pituitary adenoma. Its Ki-67 index, a measure of how many cells are actively dividing, was under 1%, indicating low growth activity.
Diabetes and Blood Pressure Drugs No Longer Needed
On the first day after surgery, her cortisol level had fallen to 34 nmol/L, an early sign that the cortisol excess had been switched off.
At her 2.5-year follow-up, she remained in clinical and biochemical remission, according to the case report's PubMed listing. She has lost 20 kilograms, about 44 pounds. She no longer takes blood pressure medication or needs glucose-lowering drugs. Her HbA1c, a measure of long-term blood sugar, fell from 108 mmol/mol before surgery to 38 mmol/mol, a level the authors described as consistent with sustained diabetes remission.
The authors noted that correctly locating the tumor spared her unnecessary investigation and treatment. Still, they cautioned that "the long-term behavior of such rare tumors remains uncertain." with no established guidelines, they called for careful hormone monitoring and continued case reporting.
A single case report cannot show how often such tumors occur or how best to find them. It also does not suggest that sinus problems are a sign of Cushing's syndrome. For the overwhelming majority of people, a stuffy nose or sinus pressure has nothing to do with hormones.
Anyone with unexplained weight gain, muscle weakness, new diabetes or high blood pressure, and other signs of excess cortisol should talk with a clinician, ideally an endocrinologist, about appropriate testing.
Key Questions Answered
Where exactly was the tumor found?
In the right maxillary sinus, an air-filled cavity in the cheek beside the nose. It was not in the pituitary gland at the base of the brain, where these tumors usually grow.
How can a pituitary tumor grow outside the pituitary gland?
Ectopic pituitary tumors arise from leftover remnants of pituitary tissue from Rathke's pouch, which forms during fetal development. Most appear along the midline of the head, which is why a maxillary sinus location is so unusual.
Why didn't the pituitary MRI find the real tumor?
The MRI showed a possible small spot on the pituitary, but blood sampling from veins draining the gland pointed to a source elsewhere. Small incidental pituitary findings are fairly common on imaging and do not always cause disease.
Did surgery cure the patient?
At 2.5 years after surgery, she remained in clinical and biochemical remission, had lost 20 kilograms, and no longer needed blood pressure or diabetes medications. Her doctors plan ongoing hormone monitoring because long-term outcomes are uncertain.
Should people with sinus symptoms worry about Cushing's syndrome?
No. This is an exceedingly rare case, and ordinary sinus problems are not a sign of Cushing's. People with signs of excess cortisol, such as unexplained weight gain and muscle weakness, should discuss testing with a clinician.
Published by Medicaldaily.com
