When my daughter was born, she had perfectly normal skin. She had a lot of diaper rashes and yeast infections (which was treated with antifungal cream) while she was in diapers though. Her doctor shrugged it off as her having a more acidic urine than normal.
When she was about 3 years old, I noticed that she had a white patch of skin on her outer vulval lips. I mentioned it to her doctor during a check-up and he didn't even offer me an explanation to what it was. He simply said "Oh that's nothing to worry about."
About 2 years later (when my daughter was 5), I noticed the white patch spreading from her outer vulval lips to the crease of her buttocks.
Now she is 8 years old and the white patch has spread from her outer vulval lips to midway down her inner thighs and it goes up the crease of her backside and covers about 1/4 of her buttocks.
The patch is completely white and devoid of pigmentation and it doesn't tan at all in the sun. She only has this one spreading patch and it causes no symptoms such as itchiness, pain, etc. I've read the groin area is a common place for Vitiligo though.
Does it sound like Vitiligo? Are there any other skin conditions with these symptoms?