MadSci Network: Medicine |
There are many possibilities for the answer to this question as the description is somewhat vague.
However, you may wish to review information on such depigmentation disorders such as vitiligo.
As well, there are a number of good on-line dermatology resources, including:
http://www.dermweb.com/dermatology_resources/external.htm
Try the links in the MadSci Library for more information on Medicine.