This large, macular darkly pigmented lesion arose rapidly from within the more lightly pigmented lesion which surrounds it. The lesion is asymmetrical, has an irregular border, very dark and irregular color, and was much larger than 6 mm in diameter. It had a thickness greater than 2 mm in depth. Although not a very accurate predictor of metastasis, thickness is the single most accurate parameter we have. 5-year survival rates with respect to melanoma depth:
<0.76mm: 95-99%
0.76-1.49mm: 80-95%
1.50-4.00mm: 60-75%
>4mm: <50%