A Sphenoidal Ectopic Pituitary Adenoma as a Differential Diagnosis of Chordoma

Abstract

Pituitary adenomas emerge from the adenohypophysis and are confined to the region of the sella turcica, however, other sites may be involved as a result of extension infiltration, or ectopic location, the ectopic involvement of the sphenoid is rare. Our case illustrated a woman patient with an ectopic invasive macroprolactinoma diagnosed as a chordoma of the skull base. In Our case, the first histological examination was consistent with a coincidental Intrasellar Chordoma and Pituitary adenoma, Immunostaining was positive for synaptophysin and prolactin with a Ki-67 index of 7%, suggestive of an invasive prolactinoma, in addition to the existence of vacuolated cells with foamy Cytoplasm resembling to hysaliphorous cells suggested the diagnosis of chordoma. However, immunohistochemical study using brachyury and S-100 protein have shown a negative stain. Thus, the diagnosis of chordoma was excluded. Thus, it is particularly important to maintain ectopic pituitary adenomas in sphenoidal or clival locations as the main differential diagnosis of chordoma; because the diagnosis can have significant implications on the management of the tumor, and can give us a golden opportunity for more conservative management (in our example managed with dopamine agonists), if the diagnosis can be made preoperatively rather than retrospectively based on histology.