PMON331 The Natural History of Pituitary Cysts in Patients with Growth Hormone Deficiency and Idiopathic Short Stature

Abstract Background Pituitary cysts may be implicated in short stature and affect growth hormone secretion. The natural history of cysts is not known in patients with GHD and ISS. Objective To characterize the progression of cyst volume (CV) and percentage of the gland occupied by the cyst (POGO) over time in GHD and ISS patients. Subjects and Methods A pediatric health system's database was queried for patients diagnosed with short stature and a cyst with at least one follow up MRI between 2007-21. Data up to 7 years after first follow up was included in this study. The mean and median follow up time were 1.32±1.24 and 1.00. Cysts with a POGO≤15% were considered small, while a POGO>15% were considered large. Results The mean and median %ΔCV for all patients for all their follow up MRIs were 38.27%±179.14 and 0%. The mean and median %ΔPOGO for all patients were 38.32%±219.85 and -5.79%. The mean and median %ΔCV for patients with a small cyst (SC) (n=34) were 61.49%±215.60 and 0%. The mean and median %ΔPOGO for patients with a SC were 61.62%±267.25 and -2.89%. The mean and median %ΔCV for patients with a large cyst(LC)(n=14) were -0.4% ±-79.25 and 0%. The mean and median %ΔPOGO for patients with a LC were -1.08%±90.50 and -15.67%. 5 of the 35(14.3%) SCs grew into LCs and stayed large while 6 of the 14 LCs shrunk into SCs. 4 cysts fluctuated between large and small: 3 started large and 1 started small. CV of patients with LCs has a significant negative correlation with time (-0.37, p=0.01). The slope of the regression line is -0.01 mm3/month. The CV of patients with SCs does not show any change in time (-0.02, p=0.84). There is no significant difference in POGO (p=0.86) or in CV (p=0.96) in GHD and ISS patients. In GHD and ISS patients, the difference in POGO is different in each group at each MRI date (p=0.02), but not in CV (p=0.38). GHD patients had an average ΔPOGO of -1.05, while ISS patients had an average ΔPOGO of 1.26. Conclusion POGO can change greatly over time. LCs tend to take up less of the gland over time. SCs tend not to change significantly over time, but a minority can still enlarge and need to be monitored. So far, there have been no significant clinical consequences related to these cysts. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.