A limited dilatation of the left breast duct is a segmental dilatation of the milk duct found during ultrasound examination of the breast, suggesting intraductal papilloma or plasmacytoid mastitis. The tumor is soft and small tumors are difficult to detect on palpation, while large tumors can be found to have a bloody discharge on the nipple when pressed. Plasmacytoid mastitis, also known as breast duct dilatation syndrome, is caused by the accumulation of secretions in the milk ducts due to hyperplasia and can be recurrent.