Hair growth on moles is usually a manifestation of pigmented nevi. Pigmented nevi can be divided into three types according to the distribution of nevus cells, namely, junctional nevi, mixed nevi, and intradermal nevi, as follows: 1. Junctional nevi: usually present at birth or occurring shortly after birth, usually relatively small, generally smooth, hairless, flat, slightly above the plane, and light to dark brown in color. 2. Mixed nevi: similar in appearance to junctional nevi, but 3.Intradermal nevus: More common in adults, the damage is mostly hemispherical raised papules and nodules with smooth or papillary surface, which can also contain hair. Generally, smooth and hairless dark pigmented nevi are more likely to be junctional nevi, while slightly elevated and hairy pigmented nevi are often mixed nevi, and hemispherical or tipped pigmented nevi are more likely to be intradermal nevi. If a pigmented nevus has malignant changes, there is often a mild local pain, burning or stinging sensation, small dots appear at the edge, such as pigmented nevus that suddenly increases in size, deepens in color, has inflammatory reaction, breaks down and bleeds, one should be alert.