Ectopic pituitary adenomas are isolated adenomas located outside the sella turcica (in variable locations) with a normal-appearing pituitary gland. These tumors are extremely rare and thought to often arise from embryological remnants along the route of Rathke’s pouch migration. Ectopic pituitary adenomas can manifest in variable clinical ways depending on hormonal activity and involvement of adjacent structures, which can present a challenge in making a diagnosis and choosing most appropriate management. In this case study, we report a 47-year-old male who presented with visual disturbances, headache, generalised weakness and hyperprolactinemia. Magnetic Resonance Imaging showed a 2 cm mass located in the clivus invading the sphenoid sinus with an intact pituitary gland. The patient underwent uncomplicated endoscopic transsphenoidal surgery, during which the intersphenoid septum was removed to reach the posterior wall and eradicate the mass successfully, while maintaining integrity of the pituitary gland. Pathological studies were consistent with prolactinoma, with no cytological malignant features. Post-surgery, symptoms notably improved, serum prolactin level dropped, and patient’s condition was satisfactory on follow-up with no long-term complications reported. The clival ectopic mass is a rare condition that it may be located adjacent to important structures and can be relatively difficult to reach. Therefore, surgery should be performed carefully to maintain the nearby structures and avoid any significant complications.

Key message: Ectopic pituitary adenoma is a rare neoplasm, located in the clivus and could mimic other clival tumors. Diagnosis and treatment could be challenging. It should be considered within the differential diagnosis of clival tumors.

Keywords: Ectopic pituitary adenoma; clival tumours; transsphenoidal surgery; prolactinoma; stalk effect; case report