THU095 Multilineage Plurihormonal (FSH LH TSH PRL ACTH) Pituitary Neuroendocrine Tumour: A Case Report

Disclosure: U.K. Mahfuza: None. V.A. Preda: None. A. Di Ieva: None. M. Rodiguez: None. Plurihormonal pituitary neuroendocrine tumors (PitNETs) are adenomas that produce more than one hormone. This is an uncommon entity. The 2022 WHO classification has differentiated these pitNETs along histological subtyping based on the tumour cell lineage, cell type, and related characteristics(1).We present a case of a 48-year-old gentleman, who initially sought attention for visual symptoms with findings of raised intraocular pressure. His ophthalmologist assessment showed temporal disc pallor. Subsequently, the MRI revealed a 30mm pituitary macroadenoma compressing the optic apparatus. He was referred to our Endocrinology service. He had a low testosterone level. He underwent an endoscopic trans-sphenoidal resection. Post-operatively he remained on testosterone replacement, the rest of the pituitary axes were intact. Pre- and post-operative visual assessment showed retinal ganglion cell loss which has negative prognostic implications. Overall, his eye pressure and visual fields improved following surgery. The histopathology diagnosis was a PitNET/adenoma with predominantly gonadotroph SF1, FSH and LH staining. In addition, there were single cells and nests of strongly TSH and PRL-positive cells scattered through the tumour, but no GH staining. There was specific ACTH staining; also in monophenotypic nests. Pit1 positive nuclei present. The TPit was negative within the tumour. There were some residual adenohypophysis cells which is a rare finding deep within a solid tumour. The tumour extended to the inferior surface of the dura. These unique features lead to uncertainty regarding the potential recurrence rate over time. Conclusion: Multilineage PitNETs are uncommon(2). The literature reports that the surgical outcome depends on the histopathology characteristics of the immunohistochemistry and transcription factors. However, PitNETs positive for SF1, FSH, LH, PRL,rl and ACTH staining are not widely reported. With the updated WHO classification and consideration of cell lineage and cell type the knowledge of these tumours will eventually improve. Follow-up and tailored management in this patient’s cohort are needed. References: (1) Asa SL, Mete O, Perry A, Osamura RY. Overview of the 2022 WHO Classification of Pituitary Tumors. Endocr Pathol. 2022 Mar;33(1):6-26.(2) Seckin Aydin, Nil Comunoglu, Merdin Lyutviev Ahmedov, Ozge Polat Korkmaz, Buge Oz, Pinar Kadioglu, Nurperi Gazioglu, Necmettin Tanriover, Clinicopathologic Characteristics and Surgical Treatment of Plurihormonal Pituitary Adenomas, World Neurosurgery, Volume 130,2019. Presentation: Thursday, June 15, 2023