8209 Silent Somatotroph Adenoma Unmasked as Pituitary Apoplexy, Disguised as Subarachnoid Hemorrhage

Abstract Disclosure: P. Vemparala: None. S. Challagulla: None. Introduction - Pituitary apoplexy is a rare and potentially life-threatening complication associated with pituitary adenomas, particularly in cases of nonfunctioning macroadenomas. Silent somatotroph adenomas, characterized by the presence of growth hormone (GH) immunoreactivity without manifesting signs and symptoms of acromegaly, are uncommon. This case report presents a distinctive instance where pituitary apoplexy served as the initial manifestation of a GH-immunoreactive tumor. CASE PRESENTATION- A 45-year-old male with a medical history of hypertension, sleep apnea, and hypogonadism sought emergency medical attention following a syncopal episode. Post-syncope, he reported severe headache and neck pain, with no other associated symptoms. Imaging revealed a subarachnoid hemorrhage and a sellar/suprasellar mass measuring approximately 2.8 x 3.6 x 4.2 cm. CT angiography ruled out an aneurysm or vascular malformation. The subarachnoid hemorrhage was attributed to hemorrhage within the sellar mass. Treatment with Nimodipine and levetiracetam was initiated. Laboratory investigations indicated normal insulin-like growth factor 1 (IGF-1) levels. Brain MRI revealed a 4.2 x 2.3 x 2.6 cm heterogeneous enhancing cystic sellar/suprasellar lesion causing mass effect on the hypothalamus and third ventricle. The patient underwent endoscopic transsphenoidal hypophysectomy, revealing a tumor that was diffusely positive for GH and synaptophysin immunostaining and negative for prolactin and ACTH. Ki67 was less than 5%, with no apparent mitotic activity, atypia, or tumor necrosis. The postoperative course was uneventful, and the patient was discharged on oral steroids. Conclusion- Silent somatotroph adenomas constitute a small percentage (2-4.2%) of pituitary adenomas. In contrast to silent gonadotroph adenomas, these tumors are more prevalent in women, tend to present earlier and exhibit higher recurrence rates. This case emphasizes the potential of silent somatotroph adenomas to manifest initially as pituitary apoplexy. It underscores the importance of vigilant post-surgical follow-up due to the possibility of recurrence. Additionally, recognizing pituitary apoplexy as subarachnoid hemorrhage is crucial for timely intervention and appropriate management. Presentation: 6/2/2024