The difference between pigmented nevus and melanoma

In many cases, these two diseases cannot be distinguished by the naked eye, and timely medical treatment and relevant examinations, such as histopathological examinations, are required to make a clear diagnosis. However, a preliminary judgment can be made through the following points:

First of all, in terms of morphology, pigmented nevi are mainly symmetrical, round or oval, relatively regular, with obvious edges and smooth small rashes, which are clearly demarcated from the surrounding tissues. Melanoma, on the other hand, is manifested as existing pigmented nevi or patches, with irregular or asymmetrical shapes, rough edges or notched or serrated edges, and unclear boundaries from the surrounding skin.

In terms of color, pigmented nevi are generally brown, brown-yellow, or black, while melanoma has other colors based on this, such as pink, blue-black, and white, and its pigments are mixed.

In terms of size, under normal circumstances, if the diameter is less than 5mm, it is more likely to be a mole. If the diameter is greater than 5mm, it is necessary to rule out the presence of melanoma. Melanoma may appear raised, hardened, or form a lump, exudate, or bleed, ulcerate and not heal. Of course, it may also be accompanied by symptoms such as itching and pain, but moles generally do not have these symptoms.