Side by side comparison of Malignant Melanoma and Melanocytic nevi Download Scientific Diagram 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, Genetics of melanocytic nevi Roh 2015 Pigment Cell & Melanoma Research Wiley Online Library 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 Lesions Basicmedical Key Differentiating between early melanomas and melanocytic nevi: A state of the art review ScienceDirect