Hi Thanks for posting on HCM Fibroglandular tissues are white on a mammogram and so are lumps.Some women have extremely dense breasts composed almost entirely of fibroglandular tissue. These women have an increased risk of getting breast cancer. Their dense breasts make cancer harder to find because the lump that looks white on the mammogram is difficult to spot because of the more extensive fibroglandular tissue.In such cases, an ultrasound or MRI may be used to spot out the lumps. Heterogenously dense breast tissue indicates that there are some areas of nondense tissue, but that the majority of the breast tissue is dense.This does not however tell us anything about cancer as this condition could be caused by premenopause or hormonal therapy. I will however suggest you see a Gynecologist for evaluation and follow up given that fibroglandular densities increase your risk of developing cancer in future. Hope my answer will help you Best regards