SAT-487 Unusual Case of Plurihormonal Pituitary Macroadenoma

Introduction Plurihormonal Pituitary adenoma is defined as an adenoma that expresses more than one hormone on immunohistochemistry. The most common combination in these adenomas includes growth hormone (GH) and prolactin (PRL). Case Description: A 65-year-old woman known to have known to have type 2 diabetes, hypertension, and class-III obesity, presented with an intractable headache and blurring vision. She also had significant worsening of her diabetes control recently despite being on insulin. CT brain and later Magnetic resonance imaging (MRI) pituitary showed a large sellar mass which measured 2.9 cm x 1.5 cm, compressing the neurophysis and the optic chiasm. Her initial investigations showed elevated corticotrophin (ACTH) level 33.6 pmol/L (1.03 - 10.7), prolactin level was high at 66.3 ng/ml (5.18 - 26.53ng/ml) and the rest of anterior pituitary hormones and IGF-1 were normal apart from primary hypothyroidism. She didn’t particularly look cushingoid, apart from the rounded face and central obesity. Cushing’s disease was confirmed on a failure of cortisol to suppress to 1mg dexamethasone (serum cortisol 783 nmol/L) and high 24-hour urinary free Cortisol at 391 ug/24 (6-123. She underwent transsphenoidal surgery (TSS) for decompression of the optic chiasm which was successful to normalize the visual fields, however, a residual tumor was still present on follow up MRI after 3 months. Interestingly, immunohistochemistry showed staining for ACTH, GH, and prolactin, Ki67 was less than 2%. Follow up evaluation showed a normal response to 1 mg suppression test and normal 24-hour urinary free cortisol. Conclusions: We present a very interesting case of plurihormonal pituitary adenoma with triple immunohistochemical stating for ACTH, GH, and Prolactin, This triple immunostaining combination is very rare and only reported in the literature once. In contrast to the other case, our patient is diagnosed in a post-menopausal woman who didn't experience florid cushingoid symptoms and she never experienced any hormonal symptoms of acromegaly or hyperprolactinemia