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.