Rathke's cleft cysts: surgical-MRI correlation in 16 symptomatic cases.

Rathke's cleft cysts (RCCs) are non neoplastic epithelial lesions of the sellar region that have been rarely reported as a clinical entity. We retrospectively reviewed the magnetic resonance imaging (MRI), intraoperative, and pathological findings of a series of 16 cases of RCCs operated at our institution since 1992. Concurrently, we discussed the different hypotheses about their embryological origin. The patients included 12 females and 4 males, 11 to 73 years of age. Endocrine disturbance was the most common presentation, followed by headaches and visual impairment. The location of the cyst was intrasellar in 7 cases, intrasellar and suprasellar in 6 cases, and suprasellar in 3 cases. The size of the cyst ranged from 8 to 26 mm (mean 12 mm). MRI signal intensity was quite variable on T1-weighted images. The cyst appeared hyperintense in 6 cases, hypointense in 6 cases, isointence in 3 cases, and heterogeneous in one case. On T2-weighted images (available in 13 cases), the signal intensity was more constant and appeared hyperintense in 11 cases and hypointense in 2 cases. After Gd-DTPA, we did not observe enhancement either of the cyst contents or of the cyst wall, but only of the pituitary gland in all patient. Most often, the pituitary gland was displaced inferiorly by the cyst located above showing a typical image of "an egg in a cup". Fifteen patients were operated upon via the transsphenoidal approach and one upon a frontal craniotomy. Intraoperatively, the cyst contents were gelatinous or thick, and dark colored. In 2 cases, it was cerebrospinal fluid-like corresponding to the signal observed on MRI. The position of the pituitary gland confirmed by surgery in 15 cases coincided with enhancement seen and MR imaging. In 13 cases where biopsy of the cyst wall was performed, it confirmed focally ciliated columnar or cuboid epithelium. A coexistent adenoma was found in one case. In conclusion, we consider that RCCs have varied MRI characteristics so that no pathognomonic sign may be observed. Except in few cases, there were no correlation between MRI and intraoperative findings. Therefore, even with MRI studies, differential diagnoses with others cystic lesions of the sellar region remains extremely difficult. The most interesting findings on MRI studies of RCCs were to locate the pituitary gland to help the surgeon to preserve pituitary tissue during surgery.