My husband has several of these popping up as of late.
He was diagnosed with skin cancer a few years ago, and he showed these to the dermatologist and the cancer surgeon...whom both told him that they were "nothing to be worried about". His started clear, then developed into a red color, and are now purple.
Your guess is as good as our's. If it's bothersome I would ask to have it removed. Don't use wart treatment! It does not look like a wart. It looks more like Dermatofibroma:
Dermatofibroma are considered to be a benign tumour, or may represent a fibrous reaction to minor trauma and insect bites.
They are firm raised papules or nodules. They vary in colour from brown to purple and red.
They occur anywhere but are seen most commonly on the lower limb. Fitzpatrick's sign may be used to aid diagnosis (dimpling of the lesion beneath the skin when subject to bilateral compression, ie gently pinching the lesion on either side).
The lesions may resemble melanomas, so biopsy may be necessary to confirm the diagnosis.
Occasionally the lesion may be removed for cosmetic reasons.
Multiple dermatofibromas may be seen in association with autoimmune disorders such as systemic lupus erythematosus, or in patients who are immunocompromised.
Hope this helps...