The primary symptoms of mammary gland hyperplasia are breast swelling and pain, which typically affect both sides but are often more pronounced on one side. Breast swelling and pain are noticeably worse before menstruation and ease after the period ends, then gradually cease until the pain reappears with the next menstrual cycle. The entire breast may feel diffusely nodular and tender to touch, with occasional lumps or increased breast pain, all related to the menstrual cycle. Additionally, mammary gland hyperplasia may also involve a small amount of nipple discharge, primarily white or brown in color.