Definition of melanoma NCI Dictionary of Cancer Terms NCI GASTROINTESTINAL HEMORRHAGE (2): Melena. Melena, the passage of black, tarry stools, usually implies blood loss greater than 500 ml originating anywhere between the oropharynx and the right hemicolon. Melena occurs most often, Melanocytic Nevus Difference Between A Birthmark Mole And Nevus Stock Illustration Download Image Now iStock Melanocyte structure and anatomy. melanin producing cells. Melanin is the pigment responsible for skin color. vector poster 29892354 Vector Art at Vecteezy Our Extra Special Skin: What is Melanin & Who Has It? PROUDLY