Freckle-like nevus, also called nigra, is not the same as freckles, which are very different pigmented skin diseases. Freckles usually develop in childhood, are hereditary, occur mainly on the face, and worsen after sun exposure. Freckle-like nevus is called black child or black child nevus in our ancient medical books. It can be distributed in any part of the skin, as well as at the junction of skin and mucous membrane or eye conjunctiva, manifesting as brown or dark brown spots, some slightly elevated, round in shape, generally about the size of a pinpoint to sesame. The surface of the spots may have slight flaking, but their delicate skin texture remains unchanged. The pigmentation is uniform and consistent, and the edges gradually become lighter and closer to the normal skin color. Freckle-like nevus mostly occurs in young age, but can gradually increase until adulthood, or suddenly appear in large numbers diffusely, or disappear after years of gradual reduction. There are also generalized freckle-like nevus and midface freckle-like nevus, which are special types of freckle-like nevus. The difference between freckle-like nevus and freckle is that nevus is darker than freckle, and its distribution is more sparse and scattered, and its color does not deepen and its number does not increase after sun exposure. In contrast, freckles are closely related to sun exposure, and their distribution is limited to sun-exposed areas. In summer, the number of freckles increases, the color deepens, and the damage becomes larger due to increased sun exposure, while in winter, the number decreases, the color becomes lighter, and the damage shrinks. Freckle-like nevus is a common hyperpigmentation disease, and sometimes it is one of the clinical manifestations of certain hereditary syndromes. There is no specific effective method of treatment. If the patient requests treatment, it can be removed surgically. Although freckles are related to heredity, they are closely related to sun exposure, and reducing sun exposure and using shading agents and sunscreens will reduce the occurrence of freckles. The occurrence of nigra is related to heredity, and if treated by oral and topical medication, the effect is extremely unsatisfactory. Some people apply physical and chemical methods to remove nigra, but they are also not promoted because of the poor effect. Whether physical methods can treat freckle-like nevus depends on its histopathology. We all know that the skin is divided into three parts: epidermis, dermis and subcutaneous tissue. If the skin damage is limited to the epidermis, it will be healed by cell division and proliferation, and no scar will be left after healing. However, if the damage is to the dermis, it will heal by connective tissue proliferation, but will leave a scar after healing. The lesion of melanin occurs at the junction of the epidermis and dermis, and the removal of melanin by various physical and chemical methods is bound to injure the dermis and may leave scars. If only the epidermal melanin is removed, the melanocytes in the superficial dermis will remain in the dermis and will continue to proliferate over time, appearing on the skin surface again. Therefore, physicochemical methods for the treatment of melanoma are not worth popularizing. At present, the physical and chemical methods of treatment for dark pigmentation are as follows: 1) surgical excision; 2) liquid nitrogen freezing; 3) electrolysis or laser cautery.