Signs of Breast Cancer Women A newly developed lump in the breast is the 6.most common sign of breast cancer, but other red flags include...Thickened, red skin in one breast.Any dimpling, puckering or retraction (small depression) of breast skin.Nipple scaling, flaking or ulceration.A newly inverted nipple.Spontaneous discharge from one nipple.A lump in the underarm.Persistent pain in one breast (this usually indicates a benign cyst, but it should be assessed). Want to Keep Reading? Continue reading with a Health Confidential membership. Sign up now Already have an account? Sign in