Assessing quality of life and depression in psoriasis patients: A cross‐sectional study

(Table 1). Almost 90% of patients developed Becker naevus before the age of 18 years. Although the proportion of patients with hypertrichosis was comparable in both sexes (60% in males vs. 48% in females), more males than females displayed hypertrichosis in the 19to 39-year age group (65% versus 39%, P = 0.0152). Moreover, more males than females at onset age of 11–18 years displayed hypertrichosis (68% versus 21%, P = 0.0021) (Table 1). The involvement of various body sites displayed gender differences. For example, more males than females had facial involvement, while more females than males had the naevus located on their extremities (Table 1). In contrast to an Italian study which reported that only 0.8% of their patients had facial involvement, our study showed this was present in 28% of chinese patients. The higher percentage of facial involvement, particularly in males, in our cohort is possibly due to the face being more vulnerable to sun exposure, especially in China where men usually do not use sunscreen while performing outdoor activities. This postulation is supported by previous observations that a larger portion of patients with Becker naevus had a history of prolonged sun exposure. In our study, all patients were from Guangzhou, China, where the annual average UV index (UVI) is 10 0.7. This compares to the annual average UV index of 4.9 0.8 in Italy, where the rate of facial involvement was 0.8% to 6.5%. Of course, other factors such as genetic background and life style may also affect the occurrence of Becker naevus on the face. The pathogenic role of sex hormone receptors, including oestrogen, androgen and progesterone receptors, has been postulated to play a role in the development of Becker naevus, as oestrogen (17b-oestradiol) increases melanin synthesis in human melanocyte cultures. In summary, we have demonstrated gender-related differences in Becker naevus: (i) the onset ages of early and late childhood; (ii) the incidence of hypertrichosis; and (iii) the involvement of various body sites, suggesting the differential role of male and female sex hormones in the development of Becker naevus at different ages. Of course, confirmation of the present results requires a larger sample size, particularly for the age groups ≤ 10 years and over 39 years old.