SUN-049 Pituitary Tumor - An Endocrine mystery

Abstract A. Mahaldar: None. H.N. Aljumaili: None. E. Punni: None. N. Shakir: None. I. Goyal: None. Metastatic tumors to the sella are rare and usually originate from breast or lung. We present a unique case of adenocarcinoma of gastroenterology origin presenting with a large sellar/suprasellar mass masquerading as pituitary macroadenoma. 83-year-old woman with past medical history of hypothyroidism, hypertension and dyslipidemia presented to Emergency Room (ER) with headaches, neck pain, cough and sinus congestion for 2-3 weeks. Physical examination and laboratory tests were unremarkable. CT of brain showed a 2.3 cm midline sellar and sphenoid sinus mass with extension into the suprasellar space without any displacement of optic apparatus. She was discharged home and scheduled to see neurosurgery as outpatient. She presented back to ER 2 weeks later with nausea, syncope, blurred vision and new bilateral horizontal diplopia. Ophthalmologic examination revealed left 3rd and right 6th nerve palsy. No other focal neurologic deficits noted. MRI brain showed a large hypoenhancing sellar mass extending into the clivus, sphenoid sinus and the suprasellar cistern with no mass effect on the optic chiasm possibly representing a large pituitary macroadenoma. Preoperative laboratory testing revealed normal anterior and posterior pituitary functions except for slightly low free thyroxine level with normal TSH. She underwent endoscopic transsphenoidal surgery with subtotal resection of sellar (and clival) mass. Pathology showed adenocarcinoma of gastroenterology origin. Postoperative MRI pituitary with contrast showed normal postoperative changes. Interestingly, normal appearing pituitary tissue within the sella was noted. CT abdomen pelvis with contrast showed focal thickening of the proximal ascending colon highly suspicious for colon cancer with numerous liver metastasis and early nodal metastasis. CT chest with contrast showed no evidence of metastatic disease. Postoperative recovery was uneventful. Labs from third postoperative day revealed ACTH 10.5 (N 7.2-63.3 pg/ml), TSH 1.8 (N 0.35-4.8 uIU/ml) FT4 0.5 (N 1.0-2.1 ng/dl), 8 AM cortisol 14.92 (N 4.1-16.60 µg/dl), sodium 138 (N 137-146 mmol/L) and Urine osmolality above 300(N 300-900 mOsm/kg). Patient had a steep functional decline and progressive failure to thrive in the next couple of weeks. She declined any further testing or treatment, elected to proceed with hospice and passed away 4 weeks later. Colon adenocarcinoma presenting as a sellar mass is rare with limited case reports in medical literature so far. Our case presented as a large pituitary macroadenoma but turned out to be a sellar/suprasellar mass of metastatic gastroenterology origin. Despite the extensive sellar/suprasellar involvement, pituitary structure and function were preserved in this case, except for thyroid studies which were more consistent with sick euthyroid disease. Sunday, June 2, 2024