12352 A Case Of Sellar Pituitary Cyst With Elevated Prolactin In A 74-Year-Old Woman

Disclosure: M.S. Tkach: None. A. Pinero-Pilona: None. A 74-year-old woman diagnosed with a pituitary mass, described as a prolactinoma, presented for follow-up care with elevated prolactin (“PL”). Initial diagnosis of a prolactinoma was 46 years prior to presentation. Prior imaging was not available. She received bromocriptine for 31 years; as PL increased to 90 on a drug holiday, bromocriptine was resumed for over a decade. After that time, PL decreased to 23, 11 years later. She was switched to cabergoline after reporting a “stuffy nose”. With PL up to 37.8 two years later, cabergoline was increased to 0.5 mg one tablet twice a week. PL subsequently dropped to 8.2 over the next two years. Upon presentation, she reported no brain imaging for “over 30 years”. She denied galactorrhea, headache, sweating, nausea, weight change, severe hypertension, hypotension, diabetes, hirsutism, fatigue, or muscle weakness. She denied visual field changes, or any formal visual field testing for over 20 years. Exam on initial presentation was unremarkable except for a diffuse goiter. Initially ordered labs were unremarkable, though A1c was 6.2%. Undiluted PL was 6.0 (confirmed on 1:100 dilution). Another PL was measured at 4.6 total and 3.8 monomeric. TSH was 1.47. Thyroglobulin antibodies and TPO were undetectable. On pituitary MRI, "the pituitary gland shows a partially empty sella turcica which is asymmetrically slightly outwardly convex on the right, possibly representing an occult arachnoid cyst versus cystic adenoma. There is a midline pituitary stalk. No parasellar abnormalities.” Scalloping of the right sellar portion was noted. Cystic changes in the pituitary in this case may be related to cystic prolactinoma, arachnoid cysts, or cystic degeneration of a prolactinoma after long-term treatment with a dopamine agonist. Cystic prolactinomas have been termed “transitional cell tumors of the pituitary” as they possess both Rathke cleft cyst and prolactinoma features. Reduced efficacy of response to medical as compared to surgical therapy in these patients has been observed. They also tend to lead to lower PL levels than solid prolactinomas, complicating diagnosis. Arachnoid cysts (“AC”) are collections of CSF within the arachnoid membrane: present in about 1.7% of the population, they account for about 1% of intracranial masses. Although an uncommon location, sellar AC have been previously described and are estimated to comprise about 3% of AC. Nonfunctioning pituitary masses or AC with stalk compression can cause elevated PL; these respond to dopamine agonist therapy, though it is not considered definitive therapy in the case of a nonfunctioning adenoma. This case represents the difficulties in management and transition of long-term care and treatment of prolactinomas as well as assessing pituitary radiological findings. Presentation: 6/1/2024