The majority of cutaneous squamous cell carcinomas arise in actinic keratoses.

Background: Retrospective studies have given conflicting results with respect to how many cutaneous squamous cell carcinomas (SCCs) arise in actinic keratoses (AK).

Objective: This study was conducted to determine what percentage of SCCs arise in AKs and to obtain more information about two histological features of SCCs, namely, thickness and ulceration.

Methods: A prospective study was done of all SCCs treated by the authors during one calendar year.

Results: Two hundred eight patients with SCC were entered into the study. An AK was contiguous with an SCC in 72% of the cases. This was taken as evidence that the SCC arose in the AK. Men presented with thicker and more ulcerated SCCs than women, but these were not statistically significant: p = 0.06 for thickness and p = 0.07 for ulceration. Ulcerated SCCs were more likely to arise on the head and neck (p = 0.02), on patients who had multiple skin cancers (p = 0.005), and on patients who had a family history of skin cancer (p = 0.03).

Conclusion: Actinic keratoses need to be removed before they turn into SCCs. The prognostic significance of ulceration of cutaneous SCCs needs to be determined.