Table 1.

Morphological classification of the PAs suitable for the ETTA approach, adapted from Barazi et al. [21].

Type 1	Ectopic peduncular or supradiaphragmatic peri-infundibular PAs, including ectopic microadenomas of the pituitary stalk or purely supradiaphragmatic macroadenomas (mostly remnant or recurrence after previous partial surgeries). These tumors are not suitable for an EEA because they have no sellar infradiaphragmatic component.
Type 2	PAs with sub-frontal extension, including macroadenomas with a supra- or infradiaphragmatic sub-frontal extension. These tumors are not fully resectable with an EEA because of their sub-frontal component, which extends anteriorly with an unfavorable angle and direction for the trans-sphenoidal approach.
Type 3	PAs presenting with a major extrasellar component, including macroadenomas with suprasellar supradiaphragmatic component exceeding the sellar volume (i.e., air balloon PAs) unlikely to be delivered through the sella with an EEA, and macroadenomas with both a large intrasellar infradiaphragmatic part and a large suprasellar supradiaphragmatic portion connected through a narrow isthmus (i.e., snowman PAs), which impairs their resection through an EEA.