What does "melanoma" mean and why is it dangerous?

Melanoma is a malignant tumor arising from melanocytes, the pigment-producing cells of the skin. The term combines melan meaning black or dark and oma meaning tumor. Melanoma is the most dangerous form of skin cancer because it can metastasize rapidly to lymph nodes, lungs, liver, brain, and bones if not caught early. Warning signs follow the ABCDE rule: asymmetry, border irregularity, color variation, diameter greater than six millimeters, and evolving shape or size. Risk factors include excessive ultraviolet exposure, fair skin, multiple moles, and family history.