Excess of nevi related to immunodeficiency: a study in HIV-infected patients and renal transplant recipients.

To assess the relationship between immune system and nevi, we studied two models of immunodeficiency caused by different mechanisms, i.e., virus and drug. Our rationale was that if an excess of nevi was found in these two epidemiologic models, it could be concluded that the excess was due to immunodeficiency itself rather than its cause. One hundred ten renal transplant recipients (RTR) were compared with age-, sex-, and phenotype-matched controls. Eighty four HIV-positive patients (HIV+) were compared with similarly matched controls. Nevi < 5 mm (N < 5) or > or = 5 mm (N > or = 5) were counted in three sites representative of regularly, intermittently, and never sun-exposed sites. The number of N < 5 was higher in RTR (p < 0.001) and in HIV+ (p < 0.001) than in respective controls. N > or = 5 were significantly higher only in RTR. These differences tended to be the same for all sites and persisted after adjustment for possible confounding factors. The incidence of atypical nevus was higher in RTR than in controls. Immunodeficiency seems to promote the occurrence of nevi. This supports the concept of immune surveillance of nevi and raises the question of whether sun-induced immune suppression plays a role in the development of nevi. As nevi are risk markers for melanoma, a higher incidence of melanoma could be expected in immunocompromised patients.