Fluid-fluid level on magnetic resonance images may predict the occurrence of pituitary adenomas in cystic sellar-suprasellar masses

The aim of the present study was to evaluate the value of identifying fluid-fluid level via preoperative magnetic resonance (MR) images in differentiating pituitary adenomas from craniopharyngioma, Rathke's cleft cyst (RCC), and other cystic sellar-suprasellar lesions. The data of 293 consecutive patients who underwent surgery for sellar-suprasellar lesions between July 2010 and December 2012 was retrospectively reviewed, and a total of 133 cystic cases were included in the present study. MR images and pathological features of all subjects were examined. Among the 133 cystic sellar-suprasellar masses, there were 78 cases of pituitary adenomas, 31 cases of craniopharyngioma, 21 cases of RCC, one case of epidermoid cyst and two cases of abscess. Fluid‑fluid levels were identified n 43 cases (55.13%) of cystic pituitary adenomas, with a single fluid level in 23 cases, two fluid levels in 8 cases, and three levels or more in 12 cases. Two cases (6.45%) of craniopharyngioma, and one case (4.76%) of RCC presented single fluid level. No instances of fluid‑fluid levels were observed in epidermoid cyst or abscess. Fluid‑fluid levels were typically exhibited on axial T2‑weighted images. The identification of fluid‑fluid level in cysts provides useful diagnostic value in distinguishing pituitary adenoma from other sellar‑suprasellar lesions. The findings of the present study suggest that a sellar-suprasellar mass with a fluid‑fluid level inside the tumor is most likely a pituitary adenoma, particularly if multiple fluid levels are observed in the same tumor. The fluid‑fluid level is typically clearly depicted on axial or sagittal MR images, suggesting subacute or chronic hemorrhage in pituitary adenomas.