Pituitary adenomas account for 10–15% of all primary intracranial neoplasms, ranking third after meningiomas and gliomas of the brain [1]. Removal of pituitary adenomas is quite challenging because of their location between the carotid arteries on the sides and the optic nerves above, which is accompanied by specific complications such as visual impairment, pituitary failure [2,3] and nasal liquorrhea, which were particularly common in the early stages of transnasal neurosurgery [4,5] some grow rapidly, spreading to extrasellar tissues. Definition of these ‘giant’ pituitary adenomas (PAs. Due to improvements in technology and accumulation of surgical experience, pituitary adenomas are now routinely removed with a rate of various complications of no more than 5–10% [6].

Pituitary adenomas are classified according to such parameters as size, location, hormonal activity, etc. (Table 1). In the National Medical Research Centre for Neurosurgery named after N.N. Burdenko, the classification proposed by B.A. Kadashev is used [7]. It is based on location and the direction of growth of the tumour. There are endosellar and endo-extrasellar adenomas, which in turn are divided into adenomas with ante-, infra-, supra-, retro-, and laterosellar growth.

Various pituitary adenomas occur with varying frequency in age groups. Thus, microprolactinomas occur more frequently in young adults 20–30 years old with female predominance, while in patients 50–60 years old without gender predominance, hormonally non-functioning macroadenomas are more common, accounting for about 40% of all pituitary tumours [7,8].