1. A method of differentiating Spitz nevi from Spitzoid malignant melanoma comprising: (a) subjecting a skin lesion sample from a patient to mass spectrometry; (b) obtaining a mass spectrometric protein profile from said sample; (c) comparing said mass spectrometric protein profile to a known normal, Spitz nevi and/or Spitzoid malignant melanoma profile; and (d) classifying said lesion as a Spitz nevi or Spitzoid malignant melanoma based on the similarities and differences between said mass spectrometric protein profile and said known profile or profiles.