There are several conditions that can mimic skin cancer. These conditions are benign lesions and are much more common than skin cancers. A fibrous papule , flesh colored papule that usually appears on or around the nose, but can be found on other parts of the face,too, can mimic basal cell carcinoma. Seborrheic keratosis is very common growth, related to age(appears after 30's) and can be confused with moles. This lesion can change color, size,shape very quickly and thats why mimic melanoma(the most malignant skin cancer).
Solar lentigoes or sun spots, also mimic melanoma and they are found on the most sun exposed areas of the body.
Moles and skin tags can mimic skin cancer, too.
Also, a differential problem can be caused by some skin infections, granuloms and ulcers.
Hope I helped!