Crooke Cell Tumor

**Semantic type:** Neoplastic Process

**Definition:** A corticotroph pituitary tumor composed of cells with Crooke hyaline change. Ring-like cytokeratin expression is typical of these neoplasms. ACTH expression is dislocated to the cell periphery and juxtanuclear region. Ultrastructurally, intermediate filaments are arranged in a ring-like pattern. (WHO)

**Synonyms:** - Crooke Cell Adenoma