A New Perspective About Diagnosing Rathke’s Cleft Cyst: Localization of the Cyst in Reference to the Pituitary Gland

Background: Rathke’s cleft cysts (RCCs) were diagnosed mostly by shape, signal intensity and enhancement characteristics on MR images. Objectives: To identify the diagnosis of RCC by an improved understanding about the cyst’s localization in reference to the pituitary gland. Patients and Methods: We retrospectively evaluated 124 patients with pituitary cystic lesions, verified surgically and histologically. The patients were divided into RCC and cystic pituitary adenoma (CPA) groups. The cysts in both groups were observed and compared, focusing on the shape and size, as well as clinical and MRI features, especially localization. Receiver-operating-characteristic (ROC) curve was performed with the clinical and MRI findings between the groups. Results: The RCC group included 90 patients (33 men) with a mean age of 40.9 years, while the CPA group included 34 patients (12 men) with a mean age of 43.5 years. On MRI, the RCCs were mostly located without shift of the pituitary stalk on the coronal view, with the superior margin of the cyst lying behind or across the junction point of the pituitary stalk on the sagittal view. The ROC curve was performed, and the following two variables exhibited good performances in diagnosing RCCs: the coronal localization (sensitivity, 91.1%; specificity, 79.4%; AUC = 0.853, 95% confidence interval: 0.778 0.910, P < 0.0001), and the sagittal localization (sensitivity, 88.9%; specificity, 91.2%; AUC = 0.889, 95% confidence interval: 0.821 0.939, P < 0.0001). Conclusion: Cyst localization, observed easily on MRI, can be used as an effective parameter for diagnosing RCC and distinguishing it from a CPA.