SUN-286 Lymphocytic Hypophysitis Mimicking Tolosa Hunt Syndrome

Introduction: Lymphocytic hypophysitis often presents with headache, hypopituitarism and visual disturbance, the latter from optic nerve compression. Rarely, it can present with diplopia from cranial nerves III, IV and VI (3.7%) and cavernous sinus involvement (1). Clinical Case: A 40 year old woman presented with left eye pain, blurry vision, ptosis and diplopia for 2 days, preceded by headache for 2 weeks. Exam was remarkable for left eye ptosis, mild proptosis, downward and outward gaze and inability to adduct her left eye. Endocrinological exam revealed free T4 0.67 ng/dL (Nl 0.70 - 1.48), TSH 0.67 ng/dL (Nl 0.70–1.48), estradiol <10 pg/mL, LH 1.0 mIU/mL, FSH 6.9 mIU/mL, prolactin 23.3 ng/ml (Nl 5.2–26.5) and IGF-1 95 ng/mL (Nl 52–328). Cortisol was not assessed as patient was already on steroids. Work-up revealed atypical ANCA (1:320) but normal C-ANA (<1:20), P-ANCA (<1:20), and the rest of immune work-up was negative including ACE, ESR, CRP, ANA, serine protease and myeloperoxidase. No systemic manifestations were present concerning for systemic autoimmune disease. CSF exam was unrevealing including a normal ACE level. MRI revealed an enlarged pituitary gland with suprasellar extension containing a focal area of T2 hyperintensity and slight T2 hypointensity at the posterior aspect of the gland. There was a midline, thickened infundibulum, enhancement of both cavernous sinuses and narrowing of right internal carotid artery without occlusion. Endoscopic endonasal transsphenoidal biopsy of pituitary lesion confirmed diagnosis of lymphocytic hypophysitis and did not meet criteria for IgG4 hypophysitis. After 4 weeks of prednisone, she had significant symptomatic improvement and repeat MRI showed decreased pituitary size but persistent abnormal enhancement of the pituitary gland and cavernous sinuses. Conclusion: The atypical and variable clinical and radiological findings of lymphocytic hypophysitis can mimic other inflammatory, infiltrative lesions, pituitary tumor with apoplexy and Tolosa Hunt Syndrome. Tolosa Hunt syndrome is an idiopathic granulomatous inflammation of the cavernous sinus involving cranial nerves II to VI and often presenting with painful ophthalmoplegia. Pituitary involvement and carotid artery narrowing have been observed (2). Our case highlights a patient with cranial nerve III palsy and significant cavernous sinus involvement, clinically concerning for Tolosa Hunt syndrome, but confirmed by biopsy to be lymphocytic hypophysitis. There are no specific serum markers to distinguish lymphocytic hypophysitis from other entities and when uncertain, diagnosis is best established by biopsy. References: 1 Caturegli P, et al. Autoimmune hypophysitis. Endocr Rev 2005, 26: 599–614. 2 A. Kambe et al. A case of Tolosa-Hunt syndrome affecting both cavernous sinuses and hypophysis and associated C3 and C4 aneurysms. Surgical Neurology 65 (2006) 304–307.