Predictors of Aggressive Clinical Phenotype among Immunohistochemically Confirmed Atypical Adenomas

Abstract

Object: In 2004, the World Health Organization (WHO) described a new category of pituitary adenomas, known as atypical adenomas, to distinguish lesions with a high propensity for local recurrence and metastasis. These served as an intermediary between commonly encountered benign pituitary adenomas and rare pituitary carcinomas. Despite this pathological diagnosis, not all atypical pituitary adenomas display clinically aggressive behavior, including local recurrence, despite medical, surgical, or radiosurgical treatment. We set out to determine which factors predict a clinically aggressive phenotype among a cohort of atypical pituitary adenomas.