Usual ductal hyperplasia (UDH) is a non-cancerous condition that develops in the breast. In this condition, there is an increased number of epithelial cells which fill and expand some of the ducts. It is a very common condition in young women but can happen to women of all ages.
Adult breast tissue is made up of small structures called glands which are organized into groups called lobules. Under certain conditions, these glands can produce milk, which is transported to the nipple by a series of small channels called ducts.
The inside of both glands and ducts is lined by specialized cells called epithelial cells which form a barrier called the epithelium. The tissue surrounding glands and ducts is called stroma and contains long, thin cells called fibroblasts.
The diagnosis of usual ductal hyperplasia can be made after a small sample of tissue is removed from the breast in a procedure called a biopsy. Usual ductal hyperplasia can also be seen in tissue removed to treat cancer or other condition in the same breast.