It could also be something simple like an infected hair follicle or a cyst. Tumours are unusual on the outside of the body. Go to a doctor for a proper diagnosis
This can be tumor. Tumor can be benign or melignine. Go to doctor and have biopsy test. It can also be wart as well. If it is wart then it viral and sexually transmitted disease. This can also be treated. Condition can be dangerous if you don't treat this growth.
I advise that any new, strange or unidentified growths, be looked at by a Dr., The sooner the better.