Depigmented patch

My 10 year old daughter developed a small depigmented patch on her left cheek in 2006 Nov.  This patch grew larger and was very stark in 2007 summer when the rest of her face was tanned.  We went to a dermatologist who did NOT think it was vitiligo but that it most likely is a post-inflammatory condition and gave us the Locoid Lipocream to use on that patch - twice a day for several weeks cut down to once a day.  The patch started to develop differnent skin tones within a month of usage and by the end of 3 months, the patch was hyper-pigmented.  Now in the past few weeks, i am seeing the hyper-pigmented patch become lighter and I see de-pigmented spots appear in the scattered around the darker patch.

What do you think could be happening with this patch?  If it were post-inflammatory would it get hyper-pigmented with usage of Locoid and now that we are not using the hypo-pigmentation process is again starting?  Or could it be something else?

Thanks!