SAT-128 - When Prolactinomas Turn Aggressive: Overcoming Management Challenges

Background: Aggressive prolactinomas are characterized by radiological invasive tumors which cannot be cured by surgery, and that have an unusually rapid rate of tumor growth despite dopamine agonist treatment and surgery. Recognition and prompt management of aggressive prolactinomas is needed.

Case: A 25-year-old woman presented with four days of worsening right eye vision, right sided headaches for months, and was found to have a 4 cm extra-axial mass centered in the right cavernous sinus with expansion of the sella and elevation of the optic chiasm. Laboratory results showed a prolactin level of 196 ng/mL. Her other pituitary hormones were normal. She denied galactorrhea or secondary amenorrhea. Her physical exam revealed ptosis of the right eye and right pupil dilation. She received one dose of bromocriptine while inpatient and was taken to the operating room the next day for transsphenoidal resection of the mass. Postoperative MRI showed incomplete resection. Pathology revealed a lactotroph cell type, with atypical features and focally increased MIB-1 proliferative index of up to 5-10%. She started cabergoline after discharge. Her headaches and vision changes improved, and prolactin levels normalized after a few months. Seventeen months after surgery she had recurrence of headaches followed by a seizure, thought to be secondary to residual tumor. A Repeat MRI showed increased tumor growth to 3.6 cm centered around the right cavernous sinus with mass effect on the medial right temporal lobe and downward displacement of the optic chiasm. After a multidisciplinary discussion, decision was made to pursue fractionated radiation therapy. She received 28 cycles between 03/2022 and 04/2022. Almost four years post radiation she remains asymptomatic on cabergoline, with normal prolactin levels and stable residual pituitary adenoma on imaging.

Conclusion: The detection of aggressive prolactinomas is essential for the appropriate management and prevention of neurological, ophthalmic, and endocrine complications. Features that can aid in their recognition include macroadenomas measuring more than 4 cm, more invasive tumors, poor hormonal and tumor burden response to dopamine agonist, and rapid recurrence after surgical resection. Additionally, immunohistochemical markers such as elevated Ki-67 >3-5%, diffuse p53 expression, low or altered expression of invasion markers such as E-cadherin, and low dopamine receptor expression are associated with aggressive prolactinomas. Clinicians should be aware of these features and, if present, anticipate the need for second- and third-line therapies in addition to dopamine agonists such as surgery, radiation, and chemotherapeutic alkylating agents like temozolomide.

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