Dopamine Agonists Can Reduce Cystic Prolactinomas

Context: Cystic prolactinomas are considered resistant to volume reduction by dopamine agonists (DAs). Although several individual case reports and small case series have suggested that DAs may reduce these lesions, larger series using standardized imaging metrics are lacking. Objective: The objectives of the study were to assess the efficacy of DAs on cyst size in patients with predominantly cystic prolactinomas and to characterize the clinical course and treatment outcomes in these patients. Design: This study was a retrospective review. Setting: The study was conducted at a tertiary referral center. Subjects: The study comprised 30 adults with cystic prolactinomas treated at Massachusetts General Hospital. Intervention(s): The interventions included treatment with Das and transsphenoidal surgery. Main Outcome Measure(s): Cyst volume calculated by a commercial software and pituitary hormone function were measured. Results: Median age was 31.5 years (interquartile range [IR] 24.5-39.2), and 24 of 30 were female. Median length of follow-up was 3.05 years (IR 1.04-5.28). Twenty-three of 30 patients received initial treatment with DAs. Median cyst volume for these patients was 435 mm(3) (IR 255-1785). Persistent cyst reduction occurred in 20 of 22 patients after DA treatment. Median cyst volume reduction was 83.5% (IR 48.8-96.2). Median time to cyst reduction was 24.6 weeks (range 2.6-73). Chiasm compression resolved in four of five patients, and nongonadal anterior hypopituitarism improved in five of six. Transsphenoidal surgery was ultimately performed in 15 of 30 patients. Conclusions: Significant cyst reduction occurred in the majority of patients treated with DAs, including those with larger lesions and chiasm compression. This study is the first formal analysis of cyst reduction with DAs in patients with cystic prolactinomas, and contrary to long-held assumptions, our results suggest that medical therapy may be effective in many such patients.