Low-Grade Glioma of the Neurohypophysis: Clinical Characteristics and Surgical Outcomes.

Abstract

Low-grade glioma (LGG) of the neurohypophysis is an extremely rare tumor arising from the pituicytes of the posterior pituitary or the infundibulum. The preoperative imaging findings of these tumors mimic those of pituitary adenomas, and radical resection is often challenging in affected patients due to the hypervascularity of the tumor. Here we describe the clinical and radiologic features of this clinical entity. We identified 8 patients with LGG of the neurohypophysis who underwent surgery at Toranomon Hospital between January 2007 and March 2017. We retrospectively reviewed the clinical and radiologic data for these patients. The patient cohort comprised 5 men and 3 women, with a mean age of 57 years. The presenting symptoms included visual disturbance in 7 patients and anterior pituitary dysfunction in 7 patients. No patient had diabetes insipidus (DI). Preoperative magnetic resonance imaging (MRI) showed a thick anterior pituitary gland located anterior to the tumor in 3 patients and flow voids on T2-weighted images in 6 patients. All patients underwent transsphenoidal surgery, and gross total resection was achieved in 4 patients. Postoperative morbidities included deterioration of anterior pituitary function in 4 patients and permanent DI in 3 patients. Anterior displacement of a thick anterior pituitary by a tumor combined with evidence of flow voids on preoperative MRI is helpful in the preoperative diagnosis of LGG of the neurohypophysis. Radical resection should be attempted in these tumors, especially during primary surgery, even though it is associated with postoperative pituitary dysfunction.