Shape, size, and thickness of the lesion
Melanoma is usually a recently developed hyperpigmented lesion, or a lightly pigmented lesion that has grown bigger over few days to months. In a few cases, it can also be an old, long-standing mole. Initially, the malignant lesion is small, but it may increase in width, thickness, and depth. There are usually changes in the lesion shape and outline, and it often looks notched.
The malignant lesion may have a nodule or a plaque, or there may be a transition from a plaque to a nodule. Superficial spreading melanoma is a thin lesion but may become palpable, and it is the most common clinical form of melanoma. The nodular type is thick with a smooth surface, but protrudes on the screen with a regular outline. Lentigo maligna is a malignant melanoma that arises on Hutchinson lentigo; the malignant part is thicker and darker than the surrounding less darker part.