Specific Imaging Findings

Rathke's cleft cyst (RCC) is located at the central portion of the pituitary gland, in the midline between the anterior and posterior lobes, and is typically bright on CT and T1-weighted MR images. T1 signal, however, varies and can be as low as that of the CSF. The size ranges from a few millimeters to 4 cm. The cyst frequently includes a suprasellar component, while in some cases the gland may be displaced inferiorly leading to “an egg in a cup” appearance. On T2-weighted images, RCC may range from hypointense to hyperintense. A helpful sign is the presence of one of more internal nodules of high T1 and low T2 signal, reflecting cholesterol and protein clusters. RCCs are not calcified and do not enhance with contrast media. A thin rim of enhancement may be present within the adjacent glandular tissue, presumably due to compression and/or inflammatory changes. Characteristic reversal of signal intensities between the anterior lobe and the RCC may be seen when comparing pre- and postcontrast MR or CT images. Single-shot fast spin-echo diffusion MR imaging may be helpful as it shows high ADC values of the RCC contents.

Pertinent Clinical Information

RCC is frequently an incidental imaging finding. Headache, hyperprolactinemia, menstrual irregularities and sexual dysfunction are common presenting symptoms. Hypopituitarism and diabetes insipidus are less frequent. When large enough, compression on the optic chiasm leads to visual field defects. Cyst removal via a transsphenoidal surgical approach is a safe and effective treatment.