A mole is essentially a dark spot on the skin due to an unusually high concentration of melanocytes, the skin cells that produce the skin pigment melanin. Moles are usually harmless, but a mole that has increased in size, thickened, darkened, changed shape, or begun bleeding should be checked by a doctor, as it may indicate the growth of a melanoma. This is a tumor of malignant melanocytes, basically a type of skin cancer.
Of course, if you have simply scratched or otherwise injured yourself, there is no cause for concern, and the treatment will be the same as for any other injury. To stop the bleeding, simply apply pressure to the wound with a clean, soft cloth for a few minutes. Later, you should wash the area and keep it clean at all times to prevent infection.
If you are not sure why the mole has started bleeding, you should visit a doctor immediately. The mole may not necessarily have turned malignant, but if it has, it needs to be removed immediately. Any delay may result in a spread of the malignant cells. Once the cancer has spread to other parts of the body, it is more difficult to cure, and in some cases is entirely incurable.
answered by G R