Superficial spreading melanoma, light micrograph. Superficial spreading melanoma (SSM) is the most common subtype accounting for almost 70% of all cutaneous melanomas. It can occur anywhere on the body but has a predilection for lower leg in females and upper back in males. It usually has a flat or slightly elevated surface than the surrounding skin, irregular margins, and variable pigmentation. The colour ranges from tan, pink, white, brown, blue, and black. The radial phase of SSM shows proliferation of atypical melanocytes arranged singly or in clusters throughout all levels of epidermis. There is usually little or no actinic damage.