Suggest Treatments For Dark Skin In My Neck Due To Thyroid Problems

hello doctor!my dark neck is my big problem it spoils my entire look though i look fair & good.when i consulted skin specialist he said its because of thyroid hormones .i developed this dark neck from my age of 12.i took course for that &its normal now.am 21 yrs old of 75 kg weight.pls help me to get rid of this problem.