SAT-273 Case of Mistaken Identity?

Abstract

Introduction Pituitary adenomas occur in 10-15% of patients and the majority are benign. Prolactinomas are the most common form of secretory pituitary adenoma. Pituitary apoplexy, a medical emergency with resulting visual loss and hormonal hyposecretion, requires rapid surgical intervention. We present a case of pituitary macroadenoma that underwent pituitary resection for acute visual disturbance which was later discovered to be caused by undiagnosed demyelinating disease.Clinical Case Patient is a 32-year-old male who presented initially with complain of fatigue and decreased libido. Work up revealed elevated prolactin level and low testosterone. MRI showed a 2x3cm pituitary macroadenoma. At moment of diagnosis, patient was otherwise asymptomatic. He was started on bromocriptine. During follow up visits, patient reported visual disturbance. First MRI in our clinic showed no suprasellar extension, no impingement of optic chiasm and nonspecific white matter disease. At that time, visual field testing showed left temporal defect in superior quadrant. Follow up MRI 1 year later continued to show a stable macroadenoma without impingement of the optic chiasm, but patient reported progressive left vision disturbance and new right vision loss. He was evaluated in the emergency room where he was treated for pituitary apoplexy with steroids and surgery. Vision improved the next day. Despite uncomplicated post-operative course, patient developed proximal muscle weakness and exam notable for diffuse motor deficit in bilateral lower extremities with hyperreflexia. Endocrinology workup was negative for hypercortisolism and ophthalmology diagnosed him with optic neuropathy. Neurology evaluation led to a diagnosis of multiple sclerosis (MS). Patient was started on natalizumab with complete resolution of all visual and muscle symptoms.Clinical lesson Our patient presented with complaints of fatigue, decreased libido and work up that showed a macroprolactinoma without MRI evidence of optic chiasm impingement. During treatment, he developed acute visual deficits that were attributed to pituitary apoplexy. This visual disturbance improved after surgery and use of high dose IV steroids, with the latter likely treating what had been an MS flare. In hindsight, ophthalmologic evaluation before surgery had shown new color blindness, a sign of optic neuropathy. Despite temporary relief, patient progressed to develop new muscle weakness and recurrent visual disturbance which led to the diagnosis of MS. Since being diagnosed and treated for MS, he has had complete resolution of his symptoms. This case stresses the importance of considering other etiologies for visual defects in patients with pituitary adenomas.