Hello,
Unfortunately the picture could not be opened but the mark can be due to pityriasis versicolor. Pityriasis versicolor (Tinea veriscolor) is a fungal infection caused by commensal yeasts in hot and humid conditions. They may be reddish brown, slightly scaly patches or ugly, depigmented areas that will not tan, especially in suntanned skin. They should be differentiated from seborrheic dermatitis and vitiligo.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I don't know if this link works but if it does, it's a picture of my arm.
http://imageshack.us/f/405/photo88.JPG/