Rathke’s cleft cysts: a 6-year experience of surgery vs. observation with comparative volumetric analysis Abstract Background Rathke’s cleft cysts (RCCs) are common sellar lesions. Their management remains controversial, particularly when small or asymptomatic. Herein we review a consecutive series of RCC patients managed with surgery or observation. Methods All patients with a new diagnosis of presumed RCC, based on MRI, from February 2012–March 2018 were retrospectively divided into observational and surgical cohorts based on an intent-to-treat model. The cohorts were compared for clinical presentation, and cyst volume. The observational cohort was followed for change in cyst size. The surgical cohort was followed for changes in endocrinopathy, visual symptoms, headache and recurrence. Results Of 90 patients (mean age 36.7 ± 19.4 years; 68% female), 60% (n = 54) were in the observational cohort and 40% (n = 36) in the surgical cohort. Average follow-up was 13 ± 23 months in the observational cohort and 24 ± 19 months in the surgical group. In comparing the cohorts, mean ages were similar with more women in the surgical group (81% vs. 56%, p = 0.04). Most patients in the observational cohort had incidentally-discovered RCCs (n = 50, 88%) as opposed to the surgical cohort (n = 6, 17%). The surgical cohort had higher rates of headache (89% vs 26%, p < 0.001), endocrinopathy (36% vs 0%, p < 0.001), and visual dysfunction (19% vs 0%, p = 0.001). Mean cyst volume and maximal cyst dimensions were greater in the surgical cohort (0.94 ± 0.77 cm3 and 14.2 ± 4.1 mm), compared to the observational cohort (0.1 ± 0.14 cm3 and 6.4 ± 3 mm), (p < 0.001). Among the 53% (n = 30/54) of patients in the observational group with follow-up, 3 (10%) had spontaneous RCC shrinkage, 1 (3%) had modest asymptomatic growth (at 10 months from initial MRI), and 87% had stable cyst size. Of the 36 patients recommended to have surgery, 89% (n = 32) did so. Post-operatively, complete or partial resolution of headache, endocrinopathy and visual dysfunction were documented in 90% (n = 28/30), 75% (n = 10/12), and 100% (n = 7/7), respectively. On follow-up MRI, 8 (22%) patients had some cyst reaccumulation, of whom 3 (8%) were symptomatic and underwent uneventful reoperation. No major complications such as hematoma, CSF leak, new endocrinopathy or visual deficits occurred. Conclusion From this consecutive series, a majority (60%) of RCCs do not appear to warrant surgical intervention and have a low risk of cyst progression. However, surgical cyst removal appears to be indicated and safe for patients with larger, symptomatic RCCs. Simple cyst drainage has a high rate of improvement in pituitary gland function, visual function and headache resolution with low complication rates and symptomatic recurrence risk. These findings stress the importance of careful case selection and potential utility of volumetric assessment for patients with RCCs.