Influence of genetic and environmental factors on melanocytic naevi: a lesson from Turner's syndrome.

Females with Turner syndrome (TS) are alleged to have increased numbers of melanocytic naevi. Although a high count of acquired melanocytic naevi (AMN) is one of the major risk factors for melanoma, this malignancy has been reported only rarely in patients with TS. The purpose of this study was to explore the effects of environmental and genetic factors on AMN count and density in TS. AMN count and density in 24 patients with TS treated with growth hormone (GH). 24 GH-treated females with GH deficiency (GHD) and 24 normal females were compared in a cross-sectional study. The average AMN density in TS was 50 naevi/m2 as compared with 18 naevi/m2 in the GHD group and 24 naevi/m2 in normal controls (P = 0.001 and P = 0.004, respectively). Duration of GH therapy did not correlate with AMN count (P = 0.44) or AMN density (P = 0.81). The pattern of distribution of naevi between constantly exposed, intermittently exposed and unexposed skin was similar in all groups. Sun exposure was the major factor that affected the regional AMN densities in the control groups, but not in the TS group. The findings of our study indicate that the effects of environmental factors on AMN count and density may vary among genetically different populations. A review of the literature suggested that melanoma is no more prevalent in TS than in the general population.