Melanoma in organ transplant patients.

Objective. The incidence of cutaneous melanoma has rapidly increased in the white population over the last decades. It has been estimated that the inc idence doubles world-wide every to years. Different risk factors have been identified, including immunosuppression. The aim of our study-was to determ ine the relative risk of developing melanoma in the organ transplant popula tion and the clinical and histological features of their melanomas. Patients and methods. This retrospective study was conducted with the colla boration of 9 University Hospital Centers: Besancon, Brest, Caen, Dijon, Li lle, Lyon, Nantes, Paris (Pitie-Salpetriere) and Rennes. A questionnaire wa s sent to the different departments of dermatology of these hospitals to ob tain information on patients who had presented a melanoma after a transplan tation between 1971 and 1997 During this period, there were 12,477 Organ tr ansplant recipients in the transplantation units of these 9 hospitals. Aver age follow-up for these patients was about 5 years and the average duration of immunosuppressive therapy was about 4.5 years. Results. Among 12,477 Organ transplant recipients, we found 17 cases of mel anoma but no data could be obtain on one case: 14 occurred in renal transpl ant recipients and 3 in cardiac transplant recipients. Clinical and histolo gical data were only available in 16 patients. The average time between tra nsplantation and diagnosis of melanoma was 63 months, but it was 5 times sh orter for 2 patients who had a past history of melanoma before transplantat ion. Two patients had a mucosal melanoma; for the cutaneous melanomas, 2 ap peared on Dubreuilh melanosis, 2 were in situ melanomas, 7 were superficial spreading melanomas and 3 were nodular melanomas. The histological review of 11 cutaneous melanomas revealed a precursor nevus in 6 cases and a weak or no stroma reaction in 7/7 cases. Complete excision of the melanoma was p erformed in all patients except one with anorectal melanoma. Four patients died of visceral metastasis within a mean 15 months. The other 12 patients are still alive with a mean 3 year course since tumor treatment. We tried t o determine the relative risk of developing melanoma in the renal transplan t population (14 cases). The number of expected cases of melanoma was 5.54, giving a relative risk of 2.5. Discussion. Only 4 studies have shown an increase in the incidence of melan oma in the renal transplant population: approximately 2 to 5-fold. In our s tudy, the 2.5-fold increase in melanoma was estimated with an average 5 yea r follow-up and an average 5 year immunosuppressive therapy. This is probab ly an underestimation of risk because we were unable to make an exhaustive collection of cases of melanomas even though transplant recipients undergo more physical examinations than a reference population. The mean latency pe riod from transplantation to melanoma diagnosis was 63 months, as in other studies. Histological examination showed that a precursor nevus is frequent with weak host cellular response to the tumor. The prognosis of these mela nomas remains difficult to predict, but in our study, it would not appear t o be as poor as expected. Discontinuation of immunosuppressive therapy woul d not appear to be necessary except in the presence of metastasis. Finally, our study demonstrates the importance of good patient follow-up, even afte r graft rejection due to the persistent risk of melanoma.