ABSTRACT
Hair, derived from the epidermis, develops around the third to fourth months of fetal life. At birth, the number of hair follicles on the scalp and on other parts of the body stabilises and no more follicles are developed. The hairs are typically broken at various lengths. Vellus hair is fine, soft and non-pigmented, and covers most of the body before puberty. Terminal hair, in contrast, is coarse, curly and pigmented. Pubertal androgens promote the conversion from vellus to terminal hair. Hair growth in excess of what is expected for age, sex and ethnicity is termed hirsutism or hypertrichosis. The nails become thickened and dystrophic. Abnormal nails may occur as a result of generalised skin disease, skin disease confined to the nails, systemic disease, fungal or bacterial infection or tumour. In paediatrics, nail clubbing is the most important of all nail abnormalities.
