It seems that your friend is having macular atrophy
It is known as anetoderma
Lesions may be flat, raised or depressed, skin-coloured or bluish-white.
There are two types... Primary and secondary.
There is no cause in primary. And secondary follows some disease.
In your friend, it seems primary anetoderma.
It may be diagnosed clinically. If needed ,skin biopsy
may be done.
There is no successful treatment to reverse the already formed lesions of anetoderma. If there are few lesions, excision should be done.
For firm diagnosis and treatment , you consult dermatologist
Dr. Ilyas patel MD