A neoplastic ductal proliferative lesion of the breast characterized by the formation of secondary lumens and prominent intraductal proliferation of a heterogeneous cellular population that may include epithelial cells, myoepithelial cells, or metaplastic apocrine cells. The disease is usual ductal breast hyperplasia (MONDO_0006484, a Monarch Disease Ontology term). Also known as: UDH, ductal breast hyperplasia of usual type, ordinary intraductal breast hyperplasia.