MODEL RELEASED. General practice doctor examining a series of brown spots on a patient's arm to check that they are moles rather than melanomas. Moles are areas of pigmented skin which may be either flat or raised. They are usually harmless, but certain types can occasionally become malignant. Melanomas are highly malignant tumours of the skin's melanocytes or pigment-forming cells. Superficial melanomas can often be successfully treated by surgery, but if the disease spreads to other parts of the body the prognosis is poor. Models: Michael Dawson (GP), Mark Ellis.