Clival Ectopic Pituitary Adenoma Causing Cushing Syndrome

The development of adenohypophysis by differentiating and detaching from the pharyngeal roof results in formation of a functional ectopic pituitary tissue around the Sella turcica. Of the ectopic sites in which pituitary adenoma occurs, clival adenomas are rare and the majority secrete prolactin. We report a case of ACTH-dependent Cushing syndrome. Magnetic resonance imaging revealed a clival mass with sphenoid sinus infiltration and ⁶⁸Gallium (Ga) Dodecane tetra acetic acid-NaI3-octreotide positron emission tomography-computed tomography showed intense uptake in the region. Postoperative immunohistochemistry revealed ACTH and T-box Protein in T-cell positivity. With literature review, we found 5 reported cases of clival ectopic pituitary adenoma with Cushing syndrome. Clinical characteristics, imaging features, histology, and management of such masses have been discussed. In conclusion, ACTH-producing clival ectopic pituitary adenomas are rare, require differentiation from neuroendocrine tumors, and remit by multimodal therapy.