Background and aim: It seems that melanocytic nevi, freckle and lentigo are more common in women with melasma, and a common genetic background may exist. In this study the prevalence and number of lentigo, freckle and melanocytic nevus were compared in women with and without melasma.
Materials and methods: In a case-control study, 120 women with melasma (case group) and 120 women without melasma (control group), matched for age, were examined by a dermatologist. The singnosis of lesions were done only by clinical observation. Data were analysed by SPSS software using chi-square (or Fisher) test and p<0.05 was considered as significant.
Results: The mean age was 29.97±6.6 years in case group and 29.7±6.7 in control group (non significant). Prevalence of freckles was higher in control group (24.3% versus 4.16%, p<0.001). 77 patients (64.1%) in case group and 20 (16.6%) of control group had lentigo (p<0.001). The mean number of lentigo in case group was 25.2 and in control group was 8 (p=0.01). The prevalence of melanocytic nevus in control group was lower than case group (96.6% versus 98.3%), but this difference was not significant. The mean number of melanocytic nevi was 2.8 in control group and 13.2 in case group (p<0.001). Campbell de Morgan angiomas were seen in 26 (21.8%) of case group and in 6 (5%) of control group (p<0.001). The mean number of these angiomas was 1 in control group and 5.2 in case group (p=0.02).
Conclusion: The prevalence and number of melanocytic nevi were higher in women who had melasma. Common factors or genes may have a role in appearing of melasma and moles.