Depigmented plaques on vulva.

A mother brought her 8-year-old daughter to our office for evaluation of vitiligo "down there". The skin eruption first appeared on her vulva a year earlier and was intermittently pruritic. The lesions were initially smaller and red, but had since lightened in color, coalesced, and had begun to spread to the perianal area. The patient's mother had received a call from her daughter's teacher who observed that her daughter was scratching the area and might be masturbating in class. WHAT IS YOUR DIAGNOSIS? HOW WOULD YOU TREAT THIS PATIENT?