Hi my daughter have few brown spots on her right arm , inner side above the wrist . First when I took her to her pediatrician he said it looks like a bruise under the skin and it should go away 7 10days . Ten days later the spots are still there . Today I took her to see a dermatologist and she said it is caused by either lemon, celery juice . Most likely she had drops of juice on her arm before she went outside and exposed her arm to the sun.