Clinical features and endoscopic findings of granular cell tumor of the sellar region: A case report and review of the literature.

Background Granular cell tumor (GCT) of the sellar region is a rare tumor of the sellar and suprasellar regions that originate from the neurohypophysis. This tumor is very difficult to differentiate from other pituitary neoplasms, such as pituitary adenoma, pituicytoma, and spindle cell oncocytoma. We report a rare case of GCT arising from the posterior pituitary of the sellar region and suggest a useful indicator for accurate diagnosis and pitfalls for surgical procedures. Case Description A 42-year-old woman was admitted to our hospital with bitemporal hemianopsia. Neuroimaging showed a large pituitary tumor in the sellar and suprasellar regions with a hypointense part on T2-weighted magnetic resonance imaging, and the enhanced anterior pituitary gland was displaced anteriorly. Laboratory findings showed mild hyperprolactinemia. Subtotal resection of the tumor was achieved using an endoscopic endonasal transsphenoidal approach. Histological findings showed round or polygonal cells with abundant granular eosinophilic cytoplasm staining strongly for thyroid transcription factor 1. The tumor was, therefore, diagnosed as a GCT of the sellar region, belonging to tumors of the posterior pituitary. After surgery, visual impairment and anterior pituitary function were improved. Follow-up neuroimaging after 1 year showed no signs of recurrence. Conclusion GCT of the sellar region is difficult to diagnose on routine neuroimaging. Therefore, accurate diagnosis requires careful identification of clinical signs, magnetic resonance imaging including hypointensity on T2-weighted imaging, and analysis of combined morphological and immunohistochemical studies.