Abstract: A method of differentiating benign melanocytic nevi from malignant melanomas is disclosed. The method generally includes treating and subjecting a skin lesion sample from a patient to mass spectrometry to obtain a mass spectrometry proteomic profile. This profile is compared to mass spectrometry proteomic profiles of reference samples, which include benign melanocytic nevi and/or malignant melanomas. Classification of the skin lesion sample as a benign melanocytic nevus or a malignant melanoma is based on similarities and/or difference between the mass spectrometry proteomic profiles.