MON-255 Oral Contraceptive Pills Mask an Aggressive Crooke’s Cell Pituitary Adenoma

Background Crooke’s cell tumors are rare and aggressive forms of pituitary adenomas. This variant of Cushing’s disease requires prompt diagnosis to avoid life-threatening complications. We report a unique case of Crooke’s cell tumor with longstanding history of irregular menstrual cycles, undiagnosed and later presented as acute unilateral ptosis and diplopia due to aggressive tumor invasion. Clinical Case 23-year-old female presented to the ER with facial swelling, left eye droop and diplopia for 3 days. She had a past medical history of oligomenorrhea and hirsutism which was normalized by oral contraceptive pills (OCP)- a combination of ethinyl estradiol and drospirenone for the last 3 years. Years prior, workup of her oligomenorrhea showed normal androgenic profile with normal DHEA-S, testosterone and 17-OH progesterone. Current exam was also significant for elevated blood pressure 200/110mmHg, BMI 37, pigmented abdominal striae and terminal hair over her chin. Labs remarkable for hypokalemia K+ 2.7 mmol/L (3.5-5.3), elevated AM cortisol 51 mcg/dL (4-20), low TSH 0.152 mcUnit/mL (0.4-5.0), low IGF-1 170 ng/mL (222-566) and FSH 1.4 mUnit/mL (1.0-9.0), with normal prolactin 24.3 ng/mL (<0.5-25) and free T4 0.87ng/dL (0.8-1.8). MRI brain showed 2.8cm homogenous enhancing soft tissue mass involving the central skull base, sphenoid sinus, sella, suprasellar cistern, and parasellar regions; displacing the optic chiasm, and invading the cavernous sinuses bilaterally and orbital apices. Post trans-sphenoidal surgery (TSS) of the pituitary mass, her left eye ptosis and diplopia resolved. Post-op MRI showed subtotal resection of the extra-axial enhancing abnormality at the central skull base with extension to multiple other anatomic spaces. Pathology read consistent with aggressive Crooke’s cell adenoma, showing invasive biologic behavior without an elevated proliferation index with positive ACTH immunohistochemistry supportive of corticotroph cell adenoma. Post-op ACTH level 73 pg/mL (6-50) and cortisol 12.5 mcg/dL (4-20), while on dexamethasone. Repeat TSS was performed for residual adenoma. Cortisol remains elevated at 15.7mcg/dL despite high dose dexamethasone taper by the neurosurgery team for post-op development of right eye ptosis. She is currently awaiting proton beam radiation therapy. Conclusion Crooke’s cell tumors are an aggressive form of pituitary adenoma for which early diagnosis is crucial for its prognosis. Our case highlights the importance of maintaining a wide differential in evaluating young women with menstrual irregularities and to include screening for Cushing’s syndrome. Empiric treatment with OCPs can mask symptoms in the earlier course of Cushing’s disease as in our patient, causing recognition only after presentation with significant tumor growth. Earlier detection could have prevented adenoma invasion and potential neurological sequelae.