This is a  skin condition called "tinea versicolor" with similar to hypo-pigmentation (loss of all pigment) of the skin caused by vitilago. 

The grey areas are a result of a poor attempt at camouflage some years ago.

It has taken several sessions over a 5-6 month period to blend the grey, white and natural skin and we will continue to make improvements, but this client is delighted with the improvement.