Surgical management considerations in cystic prolactinomas-a single center case series

The optimal treatment of prolactinomas with a predominantly cystic component remains poorly defined. The cystic tumor component is considered to respond less favorably to medical treatment, thereby advocating surgical management. The purpose of this study was to assess remission rates in surgically treated cystic prolactinomas, and to compare outcomes to similarly treated solid micro- and macroprolactinomas.

Clinical and imaging data were retrospectively compiled from 56 patients who underwent transsphenoidal resection, for symptomatic prolactinomas, from 2004 to 2018, at a single academic institution. Pituitary adenomas were subdivided according to tumor size and tumor consistency: cystic prolactinomas (>50% cystic tumor component) n = 17; solid microprolactinomas (<10 mm) n = 10; and solid macroprolactinomas (≥10 mm) n = 29. Remission was defined as a prolactin level of <10 ng/dl either immediately postoperative or at a later time point.

Median tumor size was 15 mm for cystic prolactinomas, 7 mm for solid microprolactinomas, and 25.5 mm for solid macroprolactinomas. Remission was achieved in 76% (n = 13/17) of surgically treated cystic prolactinomas, 100% (n = 10/10) of solid microprolactinomas, and 24% (n = 7/29) of solid macroprolactinomas. More than 44% of solid macroprolactinomas had a Knosp grade > 3, while most cystic prolactinomas (93.8%) and all solid microprolactinomas (100%) had a Knosp grade ≤ 2.

Despite their large tumor size (≥10 mm), high remission rates can be expected with surgically treated cystic prolactinomas. This case series of cystic prolactinomas demonstrates the successful use of transsphenoidal surgery as a favorable, and a potentially curative alternative to dopaminergic therapy in this patient population.