Melanoma refers to a pigmented nevus with malignant changes, which develops from a nevus of the nature of a junctional or mixed nevus. Although not necessarily malignant from nevus, chronic irritation and inappropriate treatment have a great relationship to the transformation of nevus into melanoma. The heel is the preferred site, followed by the head, neck and extremities. Most cases metastasize to regional lymph nodes, and bloodstream metastasis is also possible. Clinical diagnosis is based on pigmentation changes and clinical symptoms as well as biopsy of the whole specimen. The best treatment is surgical excision. Etiology and symptoms Melanoma is a malignant tumor that originates from cells that produce melanin. It is characterized by the sudden appearance or rapid growth of a nevus, a deepening of color, the appearance of comet-like tubercles or pigment rings around it, local pain, infection, ulceration or bleeding, and the appearance of enlarged lymph nodes. The tumor occurs in the lower extremities, followed by the head, neck, upper extremities, eyes, under the nails and labia. In early stage, it can metastasize to liver, brain, bone and mucous membrane by lymphatic tract and bloodstream. The onset of the disease is closely related to the nevus. The nevi on the palms of the hands, soles of the feet and eyes, which are often subject to friction, as well as those located at the junction of the epidermis and dermis, are prone to malignant transformation and are considered to be the prodromal stage of melanoma. Melanoma, also known as malignant melanoma, is a skin tumor associated with osteopathy. Benign melanoma, also known as pigmented nevus, is mostly unnoticed. Melanoma can be malignant at the outset, but usually arises from the malignant transformation of a junctional nevus. It is a more malignant tumor and is more common. The most common sites are the lower extremities, most often the feet, followed by the upper extremities, head and neck, and trunk. The cause of the disease is unknown, but some cases have a history of skin injury, burns and X-ray irradiation may be the causative factors, a few cases are related to endocrine factors, and familial tendency has also been reported. The tumor is grayish-black, nodular, soft, and sometimes ulcerated. Microscopically, the tumor cells are mostly spindle, round or polygonal in shape, with varying amounts of melanin granules in the cytoplasm and a black appearance. This tumor should be treated promptly regardless of whether it has metastasis or not. Clinical manifestations The tumor is single solid, often with an envelope, and can be black, reddish-brown in color, varying in shade, or non-pigmented. Difference between nevus and melanoma 1. Edge: The edge of nevus is smooth and clearly demarcated from the surrounding skin, while the edge of malignant melanoma is not neat and becomes jagged. In addition, the surface is rough with scaly or flaky flaking, and sometimes there is oozing or bleeding, and the lesion is higher than the skin. 2.Diameter: the diameter of nevus is usually less than 5 mm; while the diameter of malignant melanoma is larger than 5 mm. 3. Asymmetry: The two halves of a nevus are symmetrical, while the two halves of a malignant melanoma are asymmetrical. 4. Color: nevus is usually brown, brown or black; while malignant melanoma will be mixed with pink, white and blue-black on the basis of brown or tan. Among them, blue is the most ominous, and white suggests that the tumor has its own degeneration. Nodular malignant melanoma is always blue-black or gray. 5.Other symptoms: Itchy and painful nevi should also be paid special attention to. If these nevi continue to develop, ulcerative lesions are likely to appear, and the stinging or burning pain will be more obvious. How to distinguish malignant melanoma from common pigmented nevus: 1. Look at the symmetry of the nevus: draw a line with a pen and divide it into two, the common nevus is symmetrical on both sides, while malignant melanoma is mostly irregular in shape, divided into two and asymmetrical on both halves. Second, look at the edge of the mole: ordinary moles have smooth edges and are clearly demarcated from the surrounding skin, while malignant melanoma is mostly uneven and jagged. Third, look at the color of the mole: ordinary moles are mostly brown or tan or black in color, while malignant melanoma is often mixed with a variety of colors on top of the color of ordinary moles, and the color suddenly deepens, becomes black, becomes blue, or begins to fade within a few months. Four, look at the diameter of the mole: ordinary moles are generally less than 5 mm, while the diameter of malignant melanoma is mostly more than 4 mm to 6 mm. Fifth, look at the surface characteristics of the mole, texture and shape changes: ordinary moles do not change over the years, and people do not feel discomfort. In contrast, malignant melanoma often increases rapidly within a short period of time, and the surrounding skin shows inflammatory reactions, such as bleeding, ulceration, itching, difficult healing, pain, or crusting. Many new moles appear around the nevus, which is called “satellite foci” in professional terminology, and there is also enlargement of regional lymph nodes, which is a manifestation of cancer cell division and expansion, and is an important manifestation of melanoma. By mastering the above characteristics, it is not difficult to distinguish ordinary moles from malignant melanoma. However, it is difficult to distinguish a dysplastic nevus from early malignant melanoma by visual observation alone, and a biopsy should be performed to confirm the diagnosis of the suspected lesion in time.