Answer to Image Challenge

psoriasis

The answer to yesterday's diagnostic challenge is...drum roll...
# 3.  Psoriasis.

The scattered reddish, scaly, indurated papules on the lower back and buttocks are psoriasis.  The acupuncture needling of the skin produced trauma that caused Koebner's phenomenon and subsequent psoriatic flare.  This is a rare event and it was treated with a steroid cream.

Thanks for your guesses.