Surgical Outcomes in Knosp Grade 3 or 4 Macroprolactinomas: What Role Does Debulking Surgery Play?

To determine the clinical outcomes of patients who had surgery to treat Knosp 3 and 4 prolactinomas with a particular focus on hormonal outcomes.

Retrospective cohort review of South Australian patients who had surgery to treat Knosp 3 and 4 prolactinomas from January 2000 to June 2025. Tumors were resected via an endoscopic, endonasal trans-sphenoidal approach. Demographic and clinical parameters were recorded. Hormonal outcomes were measured through assessment of prolactin levels and weekly cabergoline dose preoperatively and then at 3 months postoperatively.

Of 54 total operated prolactinomas, 11 were Knosp 3 or 4 prolactinomas. Mean age at surgery was 43 years (±16, range 26-77). Knosp grade was 3 in 3 cases and 4 in 8 cases. The most common surgical indications were dopamine agonist resistance (5 cases) or intolerance (3 cases). Six patients had visual deficits preoperatively, with improvement following surgery in 5 cases (83%). PRL level prior to surgery was a mean of 82 times the upper limit of normal (±16, range 0-576), with a decline to 28 (±50, range 0-16) at 3 months postoperatively. In 6 patients on cabergoline preoperatively, 3 were on a reduced dose at 3 months postoperatively, with 3 on a stable dose.

Surgery was effective at addressing visual compromise in cavernous sinus invasive prolactinomas but had a limited effect on prolactin control and the ability to reduce dopamine agonist use.