MON-128 Challenges in the management of Silent Lactotroph Pituitary Neuroendocrine Tumour - A case report and review of literature

Abstract Disclosure: M.H. Leong: None. Y.L. Ang: None. V.D. Nga: None. C.H. Yong: None. J.Y. Wong: None. C. Tan: None. D.S. Deepak: None. Background: Pituitary neuroendocrine tumors (pitNETs) are diverse neoplasms arising from the anterior pituitary, varying in hormonal activity and clinical presentation. Silent pituitary adenomas (SPAs) are non-functioning clinically but exhibit hormone expression on histopathology. SPA, accounting for 0.6-1.65% of pitNETs, pose significant diagnostic and management challenges. Case Description: A 29-year-old woman presented with progressive visual disturbance. MRI revealed a 3.4 cm sellar-suprasellar mass with compression of the optic chiasm and invasion of the cavernous sinus. Preoperative biochemistry, including normal prolactin levels, suggested a non-functioning macroadenoma. Urgent surgical decompression was performed for optic nerve compression. Histopathology revealed a sparsely granulated lactotroph adenoma with weak prolactin immunoreactivity. Retrospective imaging analysis showed heterogeneous features, including cystic and nodular components, suggestive of a SPA. Postoperatively, the patient had a sizeable residual tumor. Despite this her prolactin levels remained normal, and a dilution study ruled out a hook effect. Dopamine agonist therapy was considered but not initiated due to patient preference and limited evidence for its efficacy in silent lactotroph pitNETs. Conclusion: Silent lactotroph pituitary adenomas differ from prolactinomas in presentation, with symptoms driven mainly by mass effects rather than hyperprolactinemia. Serum prolactin levels in such cases are often normal or mildly elevated due to the stalk effect. Silent lactotroph pituitary adenomas are often only diagnosed postoperatively via histopathological and immune transcription factor staining. While surgery remains the primary treatment for tumors causing mass effects, the role of dopamine agonists in residual or recurrent disease remains unknown. Advanced radiological techniques, alongside immunohistochemistry, are critical for accurate diagnosis and management. Presentation: Monday, July 14, 2025