Sunspots

Sunspots or solar keratoses are areas of skin that have been damaged by the sun. The area might be a single spot, or it might be an area of damage. The damage can vary in depth. If the damage continues down to the full thickness of the top layer of the skin (the epidermis) it is then classified as an intraepidermal carcinoma. If the damage extends beyond the full thickness of the epidermis, the lesion is classified as a squamous cell carcinoma.

Assessment of Severity

Most sunspots do not progress to SCC's. The damage seen in superficial sunspots can sometimes be repaired by the immune system, so early sunspots in low risk areas can be safely monitored. Signs that sunspots are deeper and more likely to progress to SCCs include

  • hyperkeratosis - excessive thickening of keratin cells (the scale cells of the outer layer of skin) 
  • inflammation - redness, swelling, pain or tenderness

Treatment

Small and superficial sunspots can be easily treated by cryotherapy or freezing the superficial layers of the skin. As sunspots become deeper, cryotherapy needs to be deeper, and treatment becomes more likely to scar and more likely to fail. As sunspots become larger or more spread out, they also become more difficult to treat by cryotherapy.

Large and deep sunspots can be more suitably treated with creams, which generally cause less scarring. These creams include efudix, picato, aldara and PDT.

Fig 1. Sunspot
Fig 1. Small solitary sunspot showing mild keratosis and mild inflammation.
Fig 2. Sunspot
Fig 2. Area of solar keratosis showing hyperkeratosis and inflammation.