Skin cancers in organ transplant recipients.

Organ transplant recipients on immunosuppressive therapy are prone to skin cancers, especially squamous cell carcinomas developing on sun-exposed areas. Their frequency increases with time after transplantation reaching 40-70% of the patients after 20 years. Squamous cell carcinomas tend to be multiple and may have a life-threatening course. Most studies concern kidney transplant recipients but new data are now available on recipients of other organs. Carcinogenic factors include mainly immunosuppressive treatments, UV light and human papillomaviruses; the role of genetic factors is more equivocal. Melanomas and other rare tumors such as Merkel cell tumors or sarcomas are also increased. Surgical excision with histological examination represents the treatment of choice. When lesions become multiple and/or aggressive, additional therapeutic methods are necessary, such as topical or oral retinoids and in some cases, reduction of the immunosuppressive treatment. Radiotherapy should be reserved to limited cases. Prevention must be undertaken by a regular dermatological examination and sun protection.