Atypical Ductal Hyperplasia: Symptoms, Diagnosis, Causes …

Atypical ductal hyperplasia (ADH)   is when a breast has more than the normal two layers of cells in the milk ducts and those additional cells are abnormal in size, shape, appearance, and growth pattern It is not breast cancer but is considered a precancerous condition. Atypical ductal hyperplasia is diagnosed with a biopsy; it cannot be detected via a breast exam or imaging.

https://www.verywellhealth.com/atypical-ductal-hyperplasia-of-the-breast-430683