Indications and outcomes of the extended endoscopic endonasal approach for the removal of "unconventional" suprasellar pituitary neuroendocrine tumors.

Objective: Pituitary neuroendocrine tumors (PitNETs) rarely harbor "unconventional" inner features such as wide intracranial extension, fibrous consistency, irregular shape, vessel encasement, and subarachnoid space invasion that increase surgical complexity, as they are not suitable for the standard transsphenoidal route. Among this subset of difficult adenomas, PitNETs harboring an unconventional suprasellar extension present peculiar surgical considerations and challenges. Herein, the authors present an international multicentric study, intending to analyze the indications and outcomes of the endoscopic endonasal transtuberculum-transplanum approach (ETTA) for the removal of these so-called unconventional PitNETs in a large cohort of patients.

Methods: PitNETs removed via an endoscopic endonasal approach (EEA) between January 2000 and December 2023 at 4 primary referral centers were retrospectively reviewed. Tumors removed via the ETTA and harboring one or more of the following unconventional suprasellar features, regardless of size and/or cavernous sinus invasion, were included in the study: irregular shape, vessel encasement, subarachnoid invasion at the supradiaphragmatic space, and firm or fibrous consistency. Clinical, radiological, surgical findings, and outcomes were reviewed.

Results: Of a total of 5138 patients with PitNETs, 257 patients underwent an ETTA (5%). Nonfunctioning PitNETs were the most common (65.4%). The most common presenting symptoms were visual field restriction (64.6%), decreased visual acuity (51%), anterior pituitary deficiency (44.8%), and endocrine hyperproduction syndromes (20.6%). All PitNETs harbored prominent suprasellar extension: 33.1% were giant and 30.7% were fibrous; the majority were multilobular (43.6%) and Knosp grade ≥ 3 (54.1%). Overall, 51.8% of patients had undergone previous treatment. The gross-total resection (GTR) rate was 49.8%. Visual field and visual acuity improved in 67.5% and 82.4% of cases, respectively. The postoperative complication rate was 19.1%. Previous treatment, vessel encasement, and Knosp grade ≥ 3 were independent risk factors affecting extent of resection. A suprasellar tumor remnant was the only significant risk factor for vascular complications, and tumor GTR the only protecting factor.

Conclusions: This is the largest series in the literature describing indications and outcome expectations of the ETTA for the removal of unconventional suprasellar PitNETs. Tumor size, shape, and consistency did not represent a limitation to favorable surgical outcomes. The difficulty in achieving total removal of unconventional PitNETs, especially in the presence of vessel encasement and recurrent lesions, should raise the awareness of the increased risk of suprasellar tumor remnant apoplexy and arterial vasospasm, particularly in tumors with subarachnoid invasion.