Cushing disease associated with Rathke's cleft cyst

Objective. Co-existence of Cushing disease and Rathke's cleft cyst (RCC) has been reported in a few cases in the literature so far. We herein describe a rare condition of Cushing disease that might originate from epithelium of RCC. Case. A 48-year-old woman was admitted to the hospital with complaints of headache, weakness, and weight gain. The patient underwent endoscopic transsphenoidal surgery due to Cushing disease. Histopathological examination revealed cyst contents and walls compatible with RCC, and normal adenohypophysis and neurohypophysis tissues. Immunohistochemical stainings with ACTH, GH, and prolactin were positive on the epithelium of the cyst. Conclusion. In our case, Cushing disease might be associated with hormonal activity derived from cyst wall of RCC or disappearance of a small microadenoma during surgical or pathological processing. According to the recent data, origin of this lesion and histogenetic link between RCC with Cushing disease could not be explained.