Challenging Knosp high-grade pituitary adenomas

Area of Science:

• Neurosurgery
• Endocrinology
• Oncology

Background:

• Parasellar extension in pituitary adenomas is a key prognostic factor for surgical outcomes.
• Adenoma invasion into the cavernous sinus (CS) impacts resectability and curability.
• Knosp high grades (3A, 3B, 4) describe varying degrees of parasellar extension and carotid artery encasement.

Purpose of the Study:

• To correlate surgical treatment options and outcomes with the biological behavior (invasion vs. displacement) of pituitary adenomas exhibiting parasellar extension.
• To analyze the relationship between Knosp grades (3A, 3B, 4) and tumor invasiveness, texture, and proliferation rates.
• To evaluate the impact of parasellar extension patterns on the extent of resection and complication rates.

Main Methods:

• Retrospective cohort analysis of 106 patients with Knosp high-grade pituitary adenomas.
• Surgery performed via endoscopic transsphenoidal approach between 2003 and 2017.
• Correlation of tumor characteristics (invasiveness, texture, WHO classification, MIB-1 proliferation) with Knosp grades (3A, 3B, 4) and surgical outcomes.

Main Results:

• Invasiveness increased with higher Knosp grades: 44% (3A) vs. 72% (3B) vs. 100% (4).
• Fibrous texture was more prevalent in grade 4 tumors.
• Higher invasiveness was observed in functioning macroadenomas (91%) compared to non-functioning ones (55%).
• Endocrine remission/gross-total resection rates were significantly higher in grade 3A (64%) than in grade 3B (33%) and grade 4 (0%).

Conclusions:

• Pituitary adenoma biological behavior significantly varies with parasellar extension patterns.
• Superior CS compartment extension (Grade 3A) is associated with lower invasiveness and better surgical outcomes.
• Distinguishing between Knosp grades 3A, 3B, and 4 is crucial for predicting invasion and guiding surgical treatment decisions.