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Differential expression of cytokeratins 8 and 20 distinguishes craniopharyngioma from rathke cleft cyst.

BACKGROUND
Craniopharyngiomas are epithelial neoplasms usually located in the sellar and suprasellar regions. Distinguishing craniopharyngioma from Rathke cleft cyst is sometimes difficult, and the distinction is clinically significant because Rathke cleft cysts have a better prognosis than craniopharyngiomas.


DESIGN
We retrieved 10 cases with a primary diagnosis of craniopharyngioma and 5 cases with a diagnosis of Rathke cleft cyst for analysis. Five cases of normal pars intermedia of pituitary glands from autopsy served as controls. We evaluated the expression patterns of a broad range of low- to intermediate-molecular weight cytokeratins (CK7, CK8, CK10, CK17, CK18, CK19, and CK20) and high-molecular weight cytokeratins (K903: a combination of CK1, CK5, CK10, and CK14; and CK5/6) in these cases.


RESULTS
Craniopharyngiomas had a cytokeratin expression pattern distinct from that of Rathke cleft cysts and pituitary gland pars intermedia: craniopharyngiomas did not express cytokeratins 8 and 20, whereas Rathke cleft cysts and pars intermedia of pituitary glands both expressed cytokeratins 8 and 20.


CONCLUSION
The differential expression of cytokeratins distinguishes between craniopharyngioma and Rathke cleft cyst, and this difference could be useful for identifying craniopharyngioma in difficult cases in which only a small biopsy is available. The different cytokeratin profiles of craniopharyngioma and Rathke cleft cyst suggest that these lesions do not come from the same origin, or that they come from a different developmental stage of the pouch epithelium.