That could be a case of stork bite, the area of the scalp that doesn't have the pigmentation like the other areas of your skin. You may have to see a dermatologist about some bleaching cream, or you may have to give the scalp a chance to tan. Do you wear hats and/or ballcaps a lot?
Have you just discovered them after shaving, or are you a long time head shaver who just discovered those spots?
Can anyone tell me what this is? Haven't noticed this before (or this bad) but my wife commented today on it.