Differentiation of pure cystic sellar lesions on magnetic resonance imaging.

BACKGROUND AND PURPOSE: Cystic pituitary adenomas and cystic craniopharyngiomas may mimic Rathke cleft cysts when there is no solid enhancing component on magnetic resonance imaging (MRI). This study aims to investigate the efficiency of MRI findings in differentiating Rathke cleft cysts from pure cystic pituitary adenoma and pure cystic craniopharyngioma.

MATERIALS AND METHODS: 109 patients were included in this study (56 Rathke cleft cysts, 38 pituitary adenomas, and 15 craniopharyngiomas). Preoperative magnetic resonance images were evaluated using 9 imaging findings. These findings include intralesional fluid-fluid level, intralesional septations, midline /off-midline location, suprasellar extension, an intracystic nodule, a hypointense rim on T2-weighted images, ≥ 2 mm thickness of contrast-enhancing wall, T1 hyperintensity and T2 hypointensity. p < 0.01 was considered statistically significant.

RESULTS: There was a statistically significant difference among groups for these 9 findings. Intracystic nodule and T2 hypointensity were the most specific MRI findings in differentiating Rathke cleft cyst from the others (98.1% and 100%, respectively). Intralesional septation and thick contrast-enhancing wall were the most sensitive MRI findings ruling out Rathke cleft cysts with 100% sensitivity.

CONCLUSION: Rathke cleft cysts can be distinguished from pure cystic adenoma and craniopharyngioma with the presence of an intracystic nodule, T2 hypointensity, the absence of the thick contrast-enhancing wall, and absence of intralesional septations.