Clinicopathological study of Rathke's cleft cysts.

The clinical, radiological and pathological characteristics of Rathke's cleft cyst are analyzed and compared with those of ciliated and goblet cell craniopharyngioma (a subset of papillary craniopharyngioma) to clarify the clinicopathological differences between these conditions. We analyzed 42 patients with Rathke's cleft cyst and 3 patients with ciliated and goblet cell craniopharyngioma. Cyst contents and MRI findings of the cyst generally reflected changing pathology of Rathke's cleft cyst. Turbid and less viscous cyst content and heterogeneous T1 and/or T2 signals on MRI sometimes represented predominance of squamous epithelium in the cyst wall. Pathological study disclosed smooth transition from ciliated columnar epithelium typical for Rathke's cleft cyst, via ciliated squamous epithelium, to squamous epithelium typical for craniopharyngioma in the same patients. Ki-67 immunostaining disclosed that the proliferative index of squamous epithelium of Rathke's cleft cyst is significantly higher than that of simple or pseudostratified epithelium of Rathke's cleft cyst (p < 0.05). In conclusion, our extensive study on Rathke's cleft cyst revealed that the high possibility of progression from Rathke's cleft cyst, in which either the cyst content or cyst wall are atypical or squamous epithelium is predominant, compared to ciliated and goblet cell craniopharyngioma and again to papillary craniopharyngioma.