What is causing this young woman's hair loss?

THIS young woman has progressive balding of her frontal scalp. Curiously, it is in a linear distribution and the scalp feels bound down in the involved area.

This is linear scleroderma, a rare condition which, if it occurs on the face, is known as en coup de sabre (sabre cut!). A biopsy showed marked sclerosis with damage to and reduction of hair follicles.

If this condition progresses to the face the sclerosis can extend through the facial muscles to the bone, giving a deep indentation. It can even involve the orbital cavity.