<ncicp:ComplexDefinition><ncicp:def-definition>A form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines.</ncicp:def-definition><ncicp:def-source>NCI-GLOSS</ncicp:def-source></ncicp:ComplexDefinition>