Dumbbell-shaped pituitary adenomas: prognostic factors for prediction of tumor nondescent of the supradiaphragmal component from a multicenter series

Abstract

OBJECTIVE Dumbbell-shaped pituitary adenomas (DSPAs) are a subgroup of macroadenomas with suprasellar extension that are characterized by a smaller diameter at the level of the diaphragma sellae opening compared with the supradiaphragmal tumor component (SDTC). Hence, DSPAs may be particularly prone to a nondescending suprasellar tumor component and risk for residual tumor or postoperative bleeding. METHODS A multicenter retrospective cohort analysis of 99 patients with DSPA operated on via direct endoscopic endonasal transsphenoidal approach between 2011 and 2020 was conducted. Patient recruitment was performed at two tertiary care centers (Medical University of Vienna and University of Southern California) with expertise in endoscopic skull base surgery. DSPA was defined as having a smaller diameter at the level of the diaphragma sellae compared with the SDTC. RESULTS On preoperative MRI, all DSPAs were macroadenomas (maximum diameter range 17–71 mm, volume range 2–88 cm3). Tumor descent was found in 73 (74%) of 99 patients (group A), and nondescent in 26 (26%) of 99 patients (group B) intraoperatively. DSPAs in group A had a significantly smaller diameter (30 vs 42 mm, p < 0.001) and significantly smaller volume (10 vs 22 cm3, p < 0.001) than those in group B. The ratio of the minimum area at the level of the diaphragmal opening in comparison with the maximum area of the suprasellar tumor component ("neck-to-dome area") was significantly lower in group A than in group B (1.7 vs 2.7, p < 0.001). Receiver operating characteristic curve analysis revealed an area under the curve of 0.75 (95% CI 0.63–0.87). At a cutoff ratio of 1.9, the sensitivity and specificity for a nondescending suprasellar tumor component were 77% and 34%, respectively. CONCLUSIONS In the present study, the neck-to-dome area ratio was of prognostic value for prediction of intraoperative tumor nondescent in DSPAs operated on via a direct endonasal endoscopic approach. Pituitary adenoma SDTC nondescent carried the inherent risk of hemorrhagic transformation in all cases.

Relationship with the diaphragm to predict the surgical outcome in large and giant pituitary adenomas

“…Recently, another classification was proposed, based on the antero-posterior, infero-superior, and lateral extensions ( 27 ). These classifications are based on tumor extension, and we agree with Micko et al ( 28 ) that one important limiting factor for tumor resection is the neck to dome ratio, determining the feasibility of an endonasal approach for these tumors and the surgical nuances of the approach necessary to achieve a maximal resection, such as the section of the diaphragm. For tumors with large suprasellar extensions, it is well known that the diaphragm can be distended and displaced markedly in a superior direction above the tumors, even up to the third ventricle ( 5 ), but true dumbbell shape tumors are caused by a low diaphragm with a narrow opening.…”

“…This result was statistically significant compared with the other morphologies. Indeed, when the diaphragm is wide open, tumor resection through an endoscopic endonasal approach may be safely performed as a large working corridor is present, and the pulsating effect of CSF during surgery or specific maneuvers to increase the intracranial pressure may help in the descent of residual tumor ( 28 , 29 ). The value of endoscopic procedures to address these tumors was also addressed by Jin et al, and the authors reported an elevated rate of GTR (90%) ( 30 ).…”

“…The extent of resection is detailed based on the relationship between the tumor and the diaphragm. intracranial pressure may help in the descent of residual tumor (28,29). The value of endoscopic procedures to address these tumors was also addressed by Jin et al, and the authors reported an elevated rate of GTR (90%) (30).…”

The Party Wall: Redefining the Indications of Transcranial Approaches for Giant Pituitary Adenomas in Endoscopic Era

“…Conversely, adenomas with a large and giant dumbbell shape impose a trans-tubercular extension of the trans-sphenoidal approach. It should involve trans-diaphragmatic access to reach the suprasellar area since, regardless of the consistency, the likelihood of a descent supradiaphragmatic component has been reported to be considerably lower in the case of significant diaphragmatic constriction [ 86 , 93 , 95 ]. A neck-to-dome cutoff ratio of 1.9 has been proven to be a reliable prognostic factor of non-descent tumors with a sensitivity of 77% [ 95 ].…”

“…It should involve trans-diaphragmatic access to reach the suprasellar area since, regardless of the consistency, the likelihood of a descent supradiaphragmatic component has been reported to be considerably lower in the case of significant diaphragmatic constriction [ 86 , 93 , 95 ]. A neck-to-dome cutoff ratio of 1.9 has been proven to be a reliable prognostic factor of non-descent tumors with a sensitivity of 77% [ 95 ]. The smaller the neck-to-dome ratio, the greater the diaphragmatic constriction.…”