Viral warts in organ transplant recipients: new aspects in therapy

The long-term success of organ transplantation depends on the prevention of allograft rejection and improvement in quality of life for the patients. This has been achieved through better immunosuppressive regimens with lower dosages and a new generation of immunosuppressive drugs. However, these immunosuppressive agents not only impair the patient's reactivity to the graft, but also to infectious organisms, thereby making them more susceptible to opportunistic pathogens. Because of this, organ transplant recipients are predisposed to epithelial malignancies and infections. The majority of transplant recipients will develop warts induced by human papillomavirus (HPV). Some of these viral warts may present with atypical histological features and may progress into squamous cell carcinomas. The risk for cutaneous cancers after transplantation is much higher than in the immunocompetent population. Current therapies for HPV-associated skin tumours mainly depend on the destruction of affected skin areas. These treatment modalities are of limited efficacy and are usually painful for the patients. A promising novel therapeutic agent is imiquimod, an immune response modifier. Clinical efficacy of imiquimod has been observed for different skin lesions, including viral warts in both immunocompetent and immunosuppressed patients.