First Depiction of Flow Voids to Differentiate Pituicytomas from Giant Adenomas.

ABSTRACT

Pituicytomas are rare low-grade glial lesions of neurohypophysis or adenohypophysis. They are often misdiagnosed as adenomas due to their similar morphology. Previous reports have underlined their nonspecific aspect. In our experience, presence of flow voids on magnetic resonance, which usually indicate hypervascularized tumors with strong arterial supply, may be a useful sign to identify pituicytomas. Unlike adenomas, pituicytomas are highly vascularized tumors. Second, we emphasize the strong enhancement of these tumors when compared with normal hypophysis, which may be another sign of their hypervascularization. Indeed, adenomas, on the opposite side, present less enhancement than normal hypophysis. This observation is corroborated by previous histologic studies that showed adenomas present less vascular density than normal pituitary glands. However, in large tumors, the normal hypophysis can sometimes not be individualized and thus the enhancement gradient between the tumor and normal tissue cannot be properly assessed. Due to their rarity, no previous reports had ever emphasized the specific signs that could allow us to differentiate pituicytomas from adenomas; however, it seems crucial due to the potential hemorrhagic complications of pituicytoma surgery.