Thank you for your question. I agree with Dr Ethan, your diagnosis is PIH ( Post inflammatory hyperpigmentation). This happened as a result of your abrasion which is an injury to your skin.
Your options include
1. Medical grade lightening creams, hydroquinone based
2. QS ND Yag laser toning at 2 weekly intervals. Your PIH will improve over the next 6 months.
3. Watchful waiting. With time and sun protection, this improves.
Hope this helps!