Squamous cell carcinomas are associated with verrucokeratotic cutaneous lesions but not with common warts in organ-transplant patients. A case-control study.

BACKGROUND: Warts are thought to be associated with the development of squamous cell carcinoma (SCC) in organ transplant patients. We investigated the association between the different types of warts and SCC in organ transplant patients.

METHODS: A prospective multicenter case-control study was conducted. Cases were patients with a kidney or heart transplant who were referred for a SCC. Controls were organ transplant patients without SCC, individually matched for age, gender, type of organ transplant (heart or kidney), skin phototype, time from transplantation, and center. Four types of warts: flat warts, verrucae vulgares (including palmo-plantar warts and common warts), verrucous papilloma, and verrucokeratotic lesions were compared between cases and controls using conditional logistic regression.

RESULTS: Ninety-nine cases and 169 controls were included. In multivariate analysis, number of rejections, azathioprine, prednisolone and anti-lymphocyte anti-serum or anti-CD3 monoclonal antibodies use, cumulative sun exposure, actinic keratosis, and verrucokeratic lesions (odds ratio [OR] 16.50; 95% confidence interval [CI] 2.82-96.80) were independently associated with SCC, whereas the association with verrucous papilloma was borderline significant (OR 2.21; 95% CI 0.97-8.15). The association between the presence of at least one of these two types of warts (verruco-keratotic lesions and verrucous papilloma) and the occurrence of SCC was highly significant (OR 18.36; 95% CI 3.03-111) when these warts were located in the same area than SCC, whereas no significant association was evidenced when these warts were located in another area (OR 1.02; 95% CI 0.13-5.79).

CONCLUSION: Verrucous papilloma and mainly verrucokeratotic lesions are strongly associated with the risk of SCC in organ transplant patients, whereas the most typical types of warts: verrucae vulgares and flat warts, are not.