The smudge can be found with the regression of any pigmented lesion, not just malignant melanoma. These are four targetoid nevi in the final stages of regressing. Notice the faint halos around the two lesions on the left. Normally the dermatoglyphics over the lesions as they regress remain intact. Histologically, only evidence of incontinence of pigment in the dermis is identified which gives them the slate gray color. Remember localizing the smudge tells you a pigmented lesion was there, it doesn't tell you what kind of a pigmented lesion was there.

For more information about malignant melanomas and other forms of skin cancer, click here.