Surgical Resection for Microprolactinomas after Failed Medical Management: An International Multi-institutional Series

Background: Prolactinomas represent the most common subtype of pituitary adenomas, the majority of which are microprolactinomas measuring less than 10 mm. Dopamine agonist (DA) treatment has remained first-line management with a reasonable 90% prolactinemia normalization rate. However, long-term DA treatment is not without side effects and many patients have contraindications to DA therapy. Furthermore, approximately a third of prolactinomas do not shrink in response to DAs, and DA pretreatment may decrease the potential for subsequent surgical cure. As endoscopic endonasal surgery (EES) continues to revolutionize surgical management of sellar lesions, we sought to assess the modern surgical cure rate for microprolactinomas and evaluate surgical resection as a potential alternative primary treatment strategy.

Methods: Retrospective chart review from 2010 to 2021 at three tertiary academic medical centers in the United States and the Netherlands of all adult patients who underwent EES for microprolactinoma was performed. Patients without preoperative and postoperative serum prolactin testing, available data on DA use, a visible lesion on preoperative MRI, or at least 1-month follow-up were excluded. Surgical “failure” was defined as a need to restart DAs, a serum prolactin level >30 ng/mL at last follow-up, tumor recurrence, or a need for reoperation.

Results: A total of 56 patients were identified who underwent EES for microprolactinoma in this multi-institutional cohort with a mean age of 32.9 years (range: 17–53) and an average 26.4 months of follow-up. The majority were female (87.5%) and had been on DAs preoperatively (98.2%). Mean maximum tumor diameter was 6.5mm with 32.1% being Knosp grade 1 or greater. The most common indication for surgery was DA intolerance (73.2%), followed by tumor unresponsiveness (19.6%), desire for pregnancy (7.1%), patient preference (7.1%), vision loss (1.8%), and apoplexy (1.8%). Gross total resection was achieved in 51 (91.1%) cases. Surgical failure was observed in 17 (30.4%) patients, with the leading causes being elevated prolactin at last follow-up in 11 patients and 7 needing to restart DAs. Multivariate logistic regression identified subtotal resection as the major independent predictor of failure to achieve surgical cure ([Table 1]). Preoperative hormonal deficiency, while significant univariate analysis, did not persist in multivariate analysis. The most common postoperative complication was transient diabetes insipidus (21.4%). Otherwise, there were two cases of postoperative panhypopituitarism (3.6%), but no instances of permanent diabetes insipidus, new visual deficits, or postoperative CSF leak.

Conclusion: With a surgical cure rate of nearly 70%, EES is a viable alternative strategy to long-term DA treatment for microprolactinoma. The main predictor of surgical cure is gross total resection, which is highly feasible via EES in experienced hands with minimal complications.

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Artikel online veröffentlicht:
07. Februar 2025