To the best of our knowledge, there are about 20 different types of skin cancers and they can be benign or malignant. The tumors can arise from either deeper or surface layers of skin or fibrous or fatty tissues. Most benign tumors grow slowly, are well defined, and do not appear to be inflamed whereas malignant ones seem to grow rapidly, ulcerate, and sometimes invade adjacent tissue.
Melanomas are skin tumors occurring most commonly on the ears and noses, inner legs, and the anus and vulva of horses. The tumors themselves are black and can also occur on the body. They are often benign but can be malignant. Melanomas can appear to be small on the outside but internally be large and invasive.