Purpose: Benign and precancerous endometrial hyperplasias (EH) are differentiated thorough two possible histomorphologic classifications: WHO (adopting the subjective evaluation of cytologic atypia) and EIN (adopting several histomorphologic parameters, evaluable subjectively, or objectively with a computerized analysis calculating a prognostic score, the D score). ACOG recommends the use of EIN system although no distinction was made between objective assessment (not widely available), and subjective assessment (more applicable in the common practice). Moreover, it is still unclear if subjective EIN system is actually preferable to WHO classification. We aimed to assess the reliability of WHO system, D score and subjective EIN system in st...