Superficial Spreading Malignant Melanoma of Skin

This article should be read in conjunction with the article Malignant Melanoma (All Sites).

• Superficial spreading melanoma (SSM) is the most common subtype and it occurs in approximately 70% of patients with a melanoma.¹
• Most common on the trunk in men and on the legs in women.
• Most often presents in individuals aged 30-50 years.

• Melanomas may arise from otherwise normal appearing skin or from within a mole or freckle, which starts to grow larger and change in appearance.
• SSM presents as a flat or slightly elevated brown lesion with variegated pigmentation (black, blue, pink, or white discoloration).
• SSM is usually greater than 6 mm in diameter and has characteristic irregular asymmetrical borders.
• SSMs tend to grow slowly but at any time they may begin to thicken or develop a nodule and progress to a vertical growth phase.
• The edge is often scalloped with dark pigment reaching into normal skin.
• Erythema and scaling are sometimes present but the lesions rarely erode the surface so oozing and bleeding are uncommon.
  
  
  
  
  
  
• There may be areas of regression that are the colour of normal skin, or white and scarred.
• During its horizontal phase of growth a melanoma is normally flat. As the vertical phase develops, the melanoma becomes thickened and raised.
• Some melanomas are itchy or tender. More advanced lesions may bleed easily or crust over.

• Prognosis tends to be good if the depth of invasion is low, especially if growth is in the horizontal (radial) phase.
• Death is unlikely if a melanoma has a tumour thickness (Breslow depth) of less than one millimetre (T1).
• About half of patients die within 5 years if their melanoma is more than 4 mm thick (T4).