UCTD doesn't "advance" to Lupus, they are not linear with each other. UCTD means you have a set of symptoms (where blood work is considered a symptom) that overlaps symptoms of other auto-immune diseases. You may share some symptoms with Lupus, you may also share symptoms with other auto-immune diseases. /en.wikipedia.org/wiki/Autoimmune_disease#Autoimmune_Diseases
What kind of Dr diagnosed the UCTD? Are you receiving any kind of treatment?
Welts can be caused by some medications, and if you are already under the care of a rheumatologist, you may want to consult the rheumy in conjunction with a dermo.
In the meantime, drink plenty of water -- it helps flush toxins from the body, and may help.
Lynnwood, Lupus & Sjogren's Moderator, Dx: 2002DIAGNOSING LUPUS & HW's LUPUS 101
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