Presentation
Incidental finding being worked up.
Patient Data
The pituitary fossa is marginally enlarged by a well-circumscribed intrinsically high T1 lesion which measures 10 x 14 x 8 mm in size. It is of high T2 signal with a low T2 signal nodule located eccentrically. On fat-saturated precontrast T1 the lesion retains its high T1 signal. The normal pituitary gland, seen only readily on dynamic imaging is stretched over the right side of the lesion, with the infundibulum is slightly deviated towards the right. Cavernous sinuses are unremarkable. Optic chiasm and optic nerves are not compressed.
The remainder of the imaged brain (please note this study has been targeted to the pituitary, and as such the whole brain has not been imaged) appears unremarkable.
Conclusion:
Characteristic appearances of a Rathke's cleft cyst.
Case Discussion
The dot sign is essentially pathognomonic for a Rathke's cleft cyst, provided appearances are otherwise compatible. It is important to note that sometimes the dot can be really large and take up the majority of the cyst.