6797 Pituitary Apoplexy as initial Presentation of IgG4-Related hypophysitis

Abstract Disclosure: M. Alameri: None. A. Alnuaimi: None. Introduction: IgG4-related hypophysitis is a rare disease due to IgG4 lymphoplasmacytic infiltration of the pituitary gland. It can either be isolated or part of a multisystemic disease. We report a rare case of pituitary apoplexy as first manifestation of IgG4-RD. Case report: A 27-year-old previously healthy male presented to emergency department with severe headache, nausea, vomiting and visual impairment. CT brain showed a large sellar suprasellar mass of 3cm with thick rim enhancement. Blood test showed evidence of central adrenal insufficiency, central hypothyroidism and secondary hypogonadism. Patient was started on hormone replacement therapy for central adrenal insufficiency and central hypothyroidism. Pituitary magnetic resonance imaging (MRI) demonstrated a 3.1 x 2.4 x 2.4 cm well-defined large sellar suprasellar mass with thick rim enhancement with intrinsic heterogeneous T2 signal with hypointense T1 signal on fat-suppressed post contrast imaging consistent with necrotic haemorrhagic suggestive of pituitary apoplexy and background of hypophysitis. Upward displacement of optic chiasm was noted without involvement of cavernous sinus. The patient was initially treated with high-dose steroids aiming for reduction of the pituitary mass. However, eventually, he underwent transsphenoidal surgery due to alternated level of consciousness. Pituitary histopathology showed that vast majority of the tissue is necrotic. A small fragment of viable anterior pituitary tissue is present, which measures up to 5.5 mm in greatest dimension which exhibited marked chronic inflammation, predominantly comprised of small lymphocytes. Plasma cells were present and staining with IgG/IgG4 revealed two high-power fields with clusters of approximately 25 and 50 IgG4 positive plasma cells, respectively. Blood test showed elevated blood IgG4 levels of >2.60 g/L (normal reference range 0.03-2.01 g/L). Case was discussed at Endocrine MDT meeting which agreed that blood tests result along with histopathology findings were in keeping with IgG4-Related hypophysitis as per the Mayo Clinic, Leporati and Japan-Korea proposed criteria. Because blood IgG4 levels were elevated, a systemic evaluation was performed. No evidence of other systemic disease found. High dose steroid therapy was initiated, which reduced remnant inflammatory sellar changes. Discussion and conclusion: IgG4-related pituitary disease should be considered as differential diagnosis in unusual presentations of pituitary apoplexy in the context of sellar suprasellar hypophysitis. Presentation: 6/2/2024