Diagnosis and Surgical Management of Exophytic Suprasellar Pituitary Adenoma Extending Over the Diaphragma Sellae and Mimicking Craniopharyngioma: A Case Report

Pituitary adenomas developing from the lateral surface of the pituitary gland are referred to as exophytic pituitary adenomas. When an exophytic pituitary adenoma extends into the suprasellar region, the tumor exhibits an atypical growth pattern that makes it difficult to distinguish it from craniopharyngiomas or other parasellar lesions on MRI. A 53-year-old woman who presented with general malaise and visual disturbances was diagnosed with a brain tumor. MRI showed a suprasellar tumor presenting as superior lobulation with reticular enhancement and partial calcification. Subsequently, endoscopic transsphenoidal surgery was performed on the patient. The suprasellar tumor was found to originate from the superior surface of the normal pituitary gland and it extended into the supra-diaphragm region. Subtotal tumor resection was achieved, and her clinical symptoms subsequently improved. Exophytic suprasellar pituitary adenomas (SPAs) are extremely rare and may be mistaken for ectopic SPAs in some cases. Contrast-enhanced fast imaging employing steady-state acquisition (CE-FIESTA) can clearly depict the connection between an exophytic SPA and the normal pituitary gland via a diaphragma sellae defect. During surgery, it was seen that the exophytic SPA and anterior lobe of the pituitary gland connected with each other directly. The tumor originated from the superior surface of the pituitary gland and extended into the supra-diaphragm region. These findings clearly confirmed the difference between exophytic SPAs and ectopic SPAs. In surgical management, an exophytic SPA needs careful consideration for resecting the tumor from encased surrounding structures without vascular and nerve injury. Ultrasonic aspiration devices may be useful for safely resecting the tumor from important structures due to tissue selection. Exophytic SPAs are distinguished from ectopic SPAs with respect to the direct connection between the tumor and the normal pituitary gland. These findings can be clearly depicted using CE-FIESTA and should be confirmed during surgery. Clinicians should be aware of the risk that exophytic SPA may extend into the supra-diaphragm region and of the difficulties of resecting the tumor encasing surrounding structures in the suprasellar region.