SAT-060 - Rare Co-Occurrence of Tolosa-Hunt Syndrome with A Pituitary Macroadenoma Leading to New-Onset Hypopituitarism

Introduction

Tolosa-Hunt Syndrome (THS) is a rare condition characterized by granulomatous inflammation of the cavernous sinus or superior orbital fissure leading to cranial nerve palsies, recurrent ophthalmoplegia, and periorbital pain. It is a diagnosis of exclusion, occurs in about one per million annually, and typically responds to corticosteroids. We present a patient with a known pituitary macroadenoma who developed ophthalmoplegia and was ultimately diagnosed with hypopituitarism and THS.

Clinical Case

A 73-year-old caucasian female was diagnosed with a pituitary macroadenoma 20 years ago, with a normal hormonal workup. MRI in 2021 showed a 1.5 cm sellar mass without optic chiasm compression or cavernous sinus involvement. She presented in April 2025 with headache and weakness; exam revealed left cranial nerve VI palsy without visual field defects. MRI indicated a 1.4 cm sellar mass invading the cavernous sinus, but no optic chiasm compression. Laboratory results showed low cortisol (1.13 ug/dL, n 6.20 - 29.00 ug/dL), low free T4 ( 0.563 ng/dL, n 0.752 - 2.000 ng/dL), low FSH (5.7 mIU/mL, n 25.8 - 134.8 mIU/mL), and low LH (0.3 mIU/mL, n 7.7 - 58.5 mIU/mL), findings consistent with new-onset hypopituitarism. She was started on hydrocortisone and levothyroxine. One month later, she returned with worsening weakness, hypotension, bradycardia, left ptosis, and cranial nerve III palsy, partly from missed hydrocortisone doses. Repeat MRI showed the pituitary mass infiltrating the cavernous sinus, abutting the optic chiasm, and new Meckel’s cave enhancement. Biopsy was deferred due to severe COPD. Lumbar puncture results were unremarkable. Empirical high-dose corticosteroids were initiated, with repeat MRI showing decreased Meckel’s cave enhancement and decreased extension into the suprasellar cistern. Imaging characteristics and rapid steroid response favored THS. High-dose corticosteroids were continued, with interval radiologic improvement. Her neurologic symptoms improved, though she remains dependent on glucocorticoids and levothyroxine.

Conclusion

This case highlights that an inflammatory process, such as THS, can develop in patients with pre-existing pituitary adenomas, mimicking tumor progression. New neurologic deficits, ophthalmoplegia, and hypopituitarism in a patient with a stable adenoma should raise suspicion for THS after excluding malignancy or other causes. Typical imaging characteristics, such as cavernous sinus enhancement, and response to corticosteroids aid diagnosis. Early recognition and prompt corticosteroid therapy can lead to symptom improvement, though pituitary dysfunction may persist.

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