Atypical Pituitary Neuroendocrine Tumor

**Semantic type:** Neoplastic Process

**Definition:** A usually aggressive and invasive pituitary neuroendocrine tumor characterized by excessive p53 immunoreactivity, increased mitotic activity, and MIB-1 proliferative index greater than 3%.

**Synonyms:** - Atypical PitNET/Adenoma - Atypical Pituitary Gland Adenoma - Atypical Pituitary Neuroendocrine Tumor/Adenoma