Clinical comparison of actinic changes preceding squamous cell carcinoma vs. intraepidermal carcinoma in renal transplant recipients.

Intraepidermal carcinoma (IEC) is a type of in situ squamous cell carcinoma (SCC), although progression of IEC is rare. We sought to investigate differences between the actinic skin changes preceding the development of both SCC and IEC. Photographs of 63 skin sites at which either SCC or IEC subsequently developed in 37 renal transplant recipients (RTRs) were examined for features of actinic change. We found that areas of skin with an actinic keratosis (AK) > 1 cm2 in size were four times more likely to develop SCC as opposed to IEC (OR = 4.42; 95% CI 1.25-15.60). Skin sites with ≥ 25% of the area affected by AK were again four times more likely to develop SCC than IEC. These results highlight the scale of visible actinic damage required for development of SCC compared with IEC, emphasizing the importance of treating areas of skin with marked visible actinic change to reduce SCC risk in RTRs.