Pituitary adenomas rarely may exist simultaneously with a Rathke's cleft cyst (RCC). This is a case of a symptomatic ACTH-secreting pituitary microadenoma adenoma associated with a RCC.

RCCs have been discovered incidentally in 11-33% of all autopsies, and are associated with less than 2 percents of the pituitary adenoma cases. Secreting microadenomas assosiated with RCCS are even more rare, I found less than 40 such cases described in published literature.

In one series, published by Sumida er al. (2002), the frequency of the combination of Rathke's cleft cyst and pituitary  adenoma was 3.5 % for pituitary adenomas and 11% for Rathke's cleft cysts. Secreting adrenocorticotrophin adenomas were present in two patients and growth hormone in six, so the frequency of ACTH-secreting adenoma combined with Rathke's cleft cyst was about 0,5%.

This case is confirmed surgically and size and  localization of cyst and microadenoma at operation was in total agreement with preoperative MR-based localization. It is important to carefully seek for possible microadenomas in hormonal disorders of pituitary origin since many of them treated surgically and presurgical identification of lesion allows not to perform costly and invasive inferior petrous sinus blood sampling to lateralize tumor.