There are several types of HPV infection: the first is common warts, which are small, hard papules on the surface of the skin that are grayish-brown or dark brown in color, with a rough, burr-like surface. The second type of wart is a small flat papule on the surface of the limb, which is smooth, brown or light white in color, and can appear homogeneous if it is scratched. The third condition is infectious molluscum contagiosum, which is caused by excessive scrubbing and other infections, and can appear on the surface of the skin as round, scattered non-fused papules, skin-colored, smooth, with an umbilical concave center.