Moles of varying sizes can be found on everyone’s body. Some of these moles do not change over the years, while others can be life-threatening: malignant melanoma – a highly malignant tumor derived from melanocytes. Because malignant melanoma looks so much like ordinary moles, patients are often misdiagnosed and mistreated. Therefore, recognizing malignant melanoma is the key to improving patient survival and cure rates. What kind of moles can be cancerous lesions? Knowledge dissemination: What is a nevus. A nevus is a pigmented plaque that manifests itself on the skin. It consists of nevus cells in the deep dermis with the appearance that the cells contain melanin vesicles. Mishandling a nevus is dangerous! Generally, moles with the following changes suggest the possibility of malignant melanoma: 1. Miscellaneous colors are often a signal of malignant lesions. Freckle-type, superficial spreading malignant melanoma is often mixed with red, white or blue in brown or black, of which blue is an ominous sign. In addition, nodular malignant melanoma is always blue-black or gray. 2. The edges are often uneven and jaggedly altered. 3. The surface is not smooth, usually very rough and accompanied by scaly or flaky desquamation, sometimes with oozing or bleeding. Skin tumors are new organisms occurring in intracutaneous or subcutaneous tissues, there are many kinds, clinically divided into benign tumors and malignant tumors. First of all, it is required to raise the vigilance to malignant tumor, pay attention to detect early symptoms and observe closely. 4. The surrounding skin may appear edema, or lose its original luster and become white or gray. When the nevus continues to develop into ulcerative lesion, it will be accompanied by oozing and bleeding, and the tingling or burning pain will be more obvious. 6. Nodules will appear around the nevus or accompanied by enlarged regional lymph nodes, which are all manifestations of the middle and late stages. There are many causes of malignant melanoma: ultraviolet radiation, malignant transformation of poorly structured nevi, heredity, trauma, endocrine abnormalities and immunodeficiency or hypoimmune function, etc. What are the signs and symptoms for the evolution from ordinary nevus to melanoma? If a nevus suddenly increases in size within a short period of time and rapidly forms a raised nodule with deepening color, it should be alerted. When the nevus expands to a certain extent, it will become papillary proliferation or rupture, forming a small ulcer (often in the shape of a spitfire), and the surface will bleed easily, ooze, or be covered with bloody crusts, and black dots, black halos, or pigmented nodules often appear around it. At the same time, the patient feels localized itching, burning and painful discomfort. If these changes occur on the body of a nevus, one should immediately seek medical attention, preferably by taking a biopsy for pathological examination to clarify the diagnosis.