I found a lump in my breast over a year ago. It grew from the size of a marble to almost the size of a golf ball. It is quite hard and irregular feeling. I had a needle biopsy done. I was told that it was a diabetic mastopathy, something that just sometimes happens to diabetics and that normally nothing is done about it. I would like to know exactly what this is and what causes it. I would also like to know if it will continue to get bigger.

First, the picture of diabetic mastopathy under the microscope is distinct and is not associated with cancer. It seems to occur in patients with type 1 diabetes who also have retinopathy and neuropathy. It may also occur rarely in patients with hypothyroidism. It is apparently an autoimmune lesion. Other than that, it is not clear why it develops or what the natural history of it is. As to whether it will grow, my opinion is that a breast surgeon would want it to be stable before any surgery might be done, as there is probably potential for some recurrence at the site of the surgery if it was to be removed. I would consult with your physician regarding management plans regarding any further enlargement. At some point, if enlargement continues and pain or disfigurement occurs, it may be reasonable to excise it.

JTL