Rathke's cleft cysts with significant squamous metaplasia - High risk of postoperative deterioration and close origins to craniopharyngioma

Background: Rathke's cleft cyst (RCC) with significant squamous and/or stratified epithelium including smooth transition from single cuboidal to squamous epithelium (tRCC) is rare and possibly represents an intermediate form to craniopharyngioma. Methods: Twelve patients with histologically confirmed tRCC were retrospectively investigated from a series of 167 cases of RCC and 96 cases of craniopharyngiomas. Clinical data were reviewed, and immunohistochemistry findings for cytokeratins and β-catenin were examined. Results: All lesions were located in the sella turcica with marked extension to suprasellar cistern. Six of the 12 patients had suffered postoperative re-enlargement, and three of these six patients required more than two additional operations and irradiation. CAM5.2 was positive in the glandular epithelium in all tRCCs and focally positive in the squamous epithelium of all these tRCCs. 34βE12 was positive in the squamous epithelium in all tRCCs and focally positive in the glandular epithelium in all but one tRCC. The findings of cytokeratin expression of tRCCs were very similar to those of craniopharyngioma. β-Catenin showed nuclear translocation in five cases. All patients with nuclear translocation of β-catenin suffered postoperative re-enlargement. Conclusions: tRCC carries an extremely high risk of re-enlargement. Cytokeratin expression resembles that in craniopharyngioma, which might indicate a very close origin of these pathologies. Nuclear translocation of β-catenin may be related to the aggressive clinical course.