I have a red non raised pimple -like area on my leg that is sore and itchy and has now developed a whitehead. I have had a number of these over the last year. The white head will last a day or two, dry up and then will eventually the spot will turn a dark purple colour and will leave a scar. These have been manily on my legs but I have had a couple on my face also. They do not always form a very large pustule, often only pinpoint.