Localized ductal dilatation in the right breast is associated with mastocytosis, benign breast nodules, and intraductal papillomas. Dilation of breast ducts is a description given during ultrasound examination of the breast in the hospital, mainly due to obstruction due to poor patency of the ducts of the breast. The duct expansion is considered to be caused by breast hyperplasia, which will compress the local breast ducts and cause local expansion when the ducts are unable to secrete mucus, or by benign breast nodules, such as breast fibroids and breast cysts, which will compress the breast ducts and cause local expansion as the tumors grow. The growth compresses the proximal end of the breast ducts, which leads to dilatation at the distal end.