Utility of intraoperative ultrasound in identifying pituitary adenoma hidden behind a cystic lesion in Cushing’s disease

Abstract

Cushing’s disease with inconclusive MRI findings presents a significant diagnostic and surgical challenge due to the difficulty in localizing the causative pituitary adenoma. This case report highlights the use of intraoperative ultrasound as an adjunct for tumor detection and successful resection in a Cushing disease patient with hidden adenoma. A 55-year-old female with a history of hypertension, diabetes, and a recent cerebral infarction presented with clinical and biochemical features of Cushing’s disease. Brain MRI revealed a 10 mm non-enhancing cystic lesion in the sella, making it difficult to confirm the underlying pathology. Inferior petrosal sinus sampling suggested a right-sided lesion, leading to an endoscopic endonasal transsphenoidal surgery. Intraoperatively, ultrasound was employed to assess the sellar region, initially identifying a cystic structure consistent with a Rathke’s cleft cyst. Following fluid drainage, ultrasound revealed an iso-echoic lesion with a distinct margin, which was subsequently resected and confirmed as a pituitary adenoma on histopathological examination. The patient experienced postoperative biochemical remission, with normalization of ACTH levels and resolution of hypertension and diabetes. This case demonstrates that intraoperative ultrasound can be a valuable tool for tumor localization in suspicious MRI-negative Cushing’s disease. By aiding in the identification of adenomas obscured by cystic lesions or surrounding structures, intraoperative ultrasound may improve surgical outcomes. Further studies are warranted to validate its efficacy in routine clinical practice.