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Đây có thể được gọi là 'vệ tinh naevi'. Naevi bẩm sinh thường có mái tóc lâm sàng rõ ràng khi sinh, nhưng sự tăng trưởng của tóc bị đầu cuối thường trở nên đặc biệt rõ ràng với thời gian. Khi độ tuổi trẻ em, các bề mặt của các mụt ruồi thường trở nên không đồng đều | 170 CHAPTER 13 Fig. 13.4 This photograph shows part of a speckled naevus. lar in appearance to true congenital naevi seem to develop at distant sites such as on the face as the child ages. These may be referred to as satellite naevi . Congenital naevi often have clinically obvious hair at birth but the growth of terminal hair often becomes particularly obvious with time. As the child ages the surface of the naevus commonly becomes uneven either mam-millated or nodular particularly giant naevi. These normal changes understandably often cause concern in families previously advised to keep the naevus under review in case of malignant change. Generally speaking as for acquired naevi the slow almost imperceptible development of nodules is reassuring whereas rapid growth over weeks is worrying. Rarely plexiform neurofibroma-like new growths develop 7 . In summary most congenital naevi become paler in colour with time and although the skin surface may become more warty and more hairy with time the majority of congenital naevi become a less serious cosmetic problem than they are at birth. In a proportion the naevus remains deeply pigmented and may actually grow proportionally in surface area and these are the most worrying cosmetically and in terms of risk of melanoma. Aetiology Congenital naevi may be more common in black or Asian children 8 . There may be an excess in females 7 . Families with more than one case of large congenital pigmented naevi have rarely been described suggesting a possible genetic origin. The presence of a large naevus was said to have existed in four second-degree relatives of 80 patients with giant naevi 20 cm in diameter reported by Ruiz-Maldonado et al. 7 . While it would seem appropriate to acknowledge this to patients seeking genetic counselling advice the significance of this remains to be established. CONGENITAL MELANOCYTIC NAEVI 171 As a genetic basis of giant CMN the concept of a lethal mutation surviving by mosacism has been proposed 9 .
