My sister is 30 and has had ovarian cysts (PCOS) since she was a child and was put on birth control pills at age 13 to help level the hormones. Although this has helped some, the cysts have not gone away and she now has to have surgery about every 2 years to remove them.
I have never heard of "leather neck" but my sister also had the same symptoms you describe. You'll notice the skin is the same between the legs and under the arms - basically anywhere the skin touches itself regularly. The medical term is acanthosis nigricans. This is a result of being insulin resistant; not diabetes. Her doctor told her it would go away with puberty but it never did. She was also an overweight child.
Just from being by my sister's side I know the concerns you have are very serious. Although your daughter is only 10, I strongly recommend you have her see a gyno and a thyroid doctor. Good news is she may not have ADD, her behaviour could be from the hormone imbalance. The behavior is more likely due to the hormone imbalance due to the ovarian cysts and not chemical imbalance which is what the ADD meds are treating.
To help eleviate some of the issues of all of the above, my sister had gastric bypass surgery 2 years ago at the urging of her gyno and family doctor. The rapid weight loss from the surgery has helped to balance her hormones and thyroid. The dark skin has lightened dramatically (and all skin tags are gone), periods are more frequent (she would go years without a period), and her general disposition is better. I don't suggest you have your 10 get gastric bypass, I just wanted to let you know where my sister is so far. A weight loss regiman will help many of the systems.
Neither my sister nor I are doctors but we both have first hand experince and have done our research and spoken with many specialists over the past 16 years.
