DISCUSSION AND CONCLUSIONS
EPAs are rare extrasellar pituitary adenomas without any correlation with the components located inside the sella turcica. They are often found along the migration pathway of Rathke’s pouch; however, the exact pathogenesis remains unclear [3, 4]. Unlike our case where the patient is a male, EPAs tend to present more in females, and most frequently between the fourth and seventh decades of life, with the mean age at diagnosis being 51.4 years old [3]. In this case, we report an EPA located in the clivus which represents the third most common location for EPAs, after the sphenoid sinus and suprasellar region [4]. Establishing the diagnosis of EPAs can be challenging as presentation varies widely depending on several factors, including anatomy, hormonal activity, and involvement/ invasion of surrounding structures [2]. When considering the differential diagnosis (DD), the clivus can be affected by a number of conditions, including lesions arising within the clivus or from adjacent structures with chordoma being the most common tumour of this region, which can be usually differentiated from EPAs on imaging inspection. However, a biopsy is usually required to confirm the diagnosis [4, 5]. Other DD include intraosseous meningioma, chondrosarcoma, solitary plasmacytomas, myelomas, astrocytoma, craniopharyngioma, germ cell tumour, non-Hodgkin’s lymphoma, melanoma, and metastases [1, 4]. Stalk effect due to a nonfunctional adenoma should be considered in DD of elevated prolactin levels. However, prolactin levels >200-250 ng/mL are suspected of prolactinomas whereas prolactin levels resulting from the pituitary stalk compression are generally <100 ng/mL and rarely exceed 250ng/mL [6]. Consistent with the presenting complaints in our report, clival EPAs, similar to other clival lesions, are known to exhibit mass effect symptoms, such as headache and focal cranial nerve palsy [7, 5]. 58% of EPAs are functional tumours. In some clival diseases, endocrinopathy may result from the infiltration of the pituitary. Clival EPAs can invade adjacent structures causing destructive features such as bone erosion, in keeping with the tumour in our case which invaded the sphenoid sinus [4, 8, 9]. Due to the complexity of EPAs, several factors should be considered for treatment, including tumour size and location, clinical manifestations, hormone-secreting type and extent of invasion [4]. The majority of EPAs are definitively diagnosed following surgery and histopathological examination [10]. Herein, trans-sphenoidal endoscopic surgery was performed as a diagnostic and therapeutic procedure. Compared with other locations (cavernous sinus, suprasellar region and the sphenoid sinus), the clival EPAs are relatively more difficult to reach; thus, detect and confirm with an endoscopic biopsy. In addition, experience in EPAs treatment is often lacking considering how rare these tumours are [4]. In conclusion, ectopic pituitary prolactinomas in the clivus are rare and the diagnosis may be difficult. However, a histological study is necessary to confirm the diagnosis especially when there are no hormonal-related symptoms.