Atypical ductal hyperplasia (ADH) is the term used for a benign lesion of the breast that indicates an increased risk of breast cancer.The name of the entity is descriptive of the lesion; ADH is characterized by cellular proliferation (hyperplasia) within one or two breast ducts and (histomorphologic) architectural abnormalities, i.e. the cells are arranged in an abnormal or atypical way. In the context of a core (needle) biopsy, ADH is considered an indication for a breast lumpectomy, also known as a surgical (excisional) biopsy, to exclude the presence of breast cancer. Signs and symptoms ADH, generally, is asymptomatic. It usually comes to medical attention on a screening mammogram, as a non-specific suspicious abnormality that requires a biopsy. Pathology ADH, cytologically, architecturally and on a molecular basis, is identical to a low-grade ductal carcinoma in situ (DCIS); however, it has a limited extent, i.e. is present in a very small amount (< 2 mm). ...