You avoid the use of hydroquinone
, you may develop exogenous ochronosis..
In your case, the melanin might be in dermis..dermal hypermelanosis
,so there is poor respone...
I think, you may go for laser therapy
or deep chemical peeling.
But, this should be done by expert dermatologist
Avoid sun exposure, you may use sun screen like sunmask aqua gel.
Oral glutathion, vitamin C and nicotinic acid may be helpful to reduce the pigmentation.
I hope you got my answer.
Dr. Ilyas Patel MD