The incidence of actinic keratoses (AK) is increased in organ transplant recipients, occurring in 38% of patients after 5 years of immunosuppression. AK in transplant recipients progress more rapidly to squamous cell carcinoma (SCC), which in turn are more aggressive and have an increased tendency to metastasize. The most important risk factors for the development of AK are the degree and length of immunosuppression, human papilloma virus infection and sun exposure. It is particularly important to treat AK early and aggressively in transplant recipients in order to minimize progression to invasive SCC.

Traditionally, cryotherapy with liquid nitrogen has been the most frequent treatment for both individual and multiple AK. The other common treatments for AK include topical 5-fluorouracil (5-FU), topical retinoids and topical diclofenac, which will be discussed in this chapter, and newer treatments including imiquimod cream and photodynamic therapy that have been discussed in chapters 44 and 45, respectively. Table 43.1 outlines the cure rates, advantages, and disadvantages of these medications. Compared with cryotherapy, all of these modalities are advantageous as field treatments of large areas of photodamage with multiple or confluent AK. A “field” treatment is one in which an entire area of photodamaged skin, including AK as well as intervening skin, is treated rather than only the clinically apparent AK. Because these treatments target both clinically evident AK as well as subclinical AK, they may reduce the potential for development of SCC on a broad area of photodamaged skin.