Prevalence and distribution of melanocytic naevi on the scalp: a prospective study.

BACKGROUND: Few studies have examined the incidence and characteristics of naevi on the scalp. Most studies of scalp naevi have been performed in children, whose incidence of scalp naevi is relatively high, at about 0.5-11.7\% of the total body count of common naevi. OBJECTIVES: To investigate the prevalence and distribution of scalp melanocytic naevi in patients of all ages. To our knowledge, ours is the first study to analyse in detail the relationships between melanocytic naevi on the scalp and total body naevi and total body atypical naevi. METHODS: We conducted a prospective study of patients visiting the dermatology outpatient clinic at the University of Florence, for examinations unrelated to the presence of naevi or melanoma. The study enrolled 795 subjects (417 females; 52.4\%), with a median age of 35 years (range 4-80). RESULTS: The number of melanocytic naevi on the scalp increased significantly (r = 0.2057, P = 0.0008) as the number of total body melanocytic naevi increased and a correlation was found between the number of clinically atypical total body naevi and the number of scalp naevi. Relatively few naevi (15.5\%) were located at the frontal region compared with other regions of the scalp, although the frontal region is more exposed to ultraviolet (UV) rays. Compared with subjects without alopecia, whose hair shields the scalp from UV rays, subjects with androgenetic alopecia showed no significant increase in number of scalp naevi. CONCLUSIONS: Despite practical difficulties, early diagnostic screening for melanoma or screening during follow-up examination for previous melanoma should involve examination of the entire skin surface, scalp included.