Hello, this is Dr K.. Answers are not medical advice and do not constitute a doctor/patient relationship. I look forward to helping you today.
This looks like postinflammatory hyperpigmentation. I wonder if you were circumcised due to problems with infection or inflammation. It may be the case, since you were circumcised at age 10. It is just a color change and nothing to be concerned about. Its the underlying pigmentationof the skin and cannot be changed. You may be able to seek the consultation of a dermatologist for laser therapy options to lighten it.
Thanks for your help. It has certainly put my mind at ease