Exophthalmos and Cushing's Syndrome
A woman experienced red, irritated and bulging eyes. She saw an ophthalmologist who strongly suspected Graves’ ophthalmopathy. However, the patient did not have and never had hyperthyroidism.
Indeed, she had primary hypothyroidism optimally treated with levothyroxine. Her thyroid stimulating hormone level was 1.197 uIU/mL.
An MRI of the orbits showed normal extraocular muscles without thickening, but there was mild proptosis and somewhat increased intraorbital fat content. Both thyroid-stimulating immunoglobulins as well as thyrotropin receptor antibodies were negative.
The patient presented to her primary care physician a few months later. She had experienced a 40-lb weight gain over only a few months and also had difficult-to-control blood pressure.
After failing to respond to several antihypertensive medications, her primary care physician astutely decided to evaluate for secondary causes of hypertension. A renal ultrasound was ordered to evaluate for renal artery stenosis, and the imaging identified an incidental right-sided adrenal mass. A CT confirmed a 3.4-cm right-sided adrenal mass. Her morning cortisol was slightly high at 24.7 ug/dL (4.3 – 22.4) and her adrenocorticotropic hormone was slightly low at 5 pg/mL (10-60).
At this point I saw the patient in consultation. She definitely had many of the expected clinical exam findings of Cushing’s syndrome, including increased fat deposition to her abdomen, neck, and supraclavicular areas, as well as striae. Her 24-hour urine cortisol was markedly elevated at 358 mcg/24hrs (< 45) confirming our suspicions.
She asked me, “Do you think that my eye problem could be related to this?”
“I’ve not heard of it before,” I replied, “but that doesn’t mean there can’t be a connection. Wouldn’t it be wonderful if your eyes got better after surgery?”
The patient underwent surgery to remove what fortunately turned out to be a benign adrenal adenoma.
When we saw her in follow-up 2 weeks later, her blood pressures were normal off medication and her eye symptoms had improved. I had a medical student rotating with me, so I suggested that we do a PubMed literature search.
The first article to come up was a case report titled “Exophthalmos: A Forgotten Clinical Sign of Cushing's Syndrome.” Indeed, not only did Harvey Cushing describe this clinical finding in his original case series in 1932, but others have reported that up to 45% of patients with active Cushing’s syndrome have exophthalmos.
The cause is uncertain but is theorized to be due to increased intraorbital fat deposition. Unlike exophthalmos due to thyroid disease, the orbital muscles are relatively normal — just as they were with our patient.
Some of you may have seen exophthalmos in your Cushing’s patients; however, this was the first time I had seen it. Just because one has not heard of something, does not mean it could never happen; no one knows everything. “When in doubt, look it up” is a good habit for both attending physicians and their students.
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