Giant Congenital Hairy Naevus
This shows a medium sized congenital naevus, present from birth.
This shows a giant congenital naevus treated with excision and split thickness skin grafting. In this case, the naevus can be seen to be recurring on the upper thigh. Note the multiple naevi present on the unaffected skin.
This shows a medium sized congenital hairy naevus. The hair on this lesion was of similar density to that found elsewhere on the scalp. It was treated by excision and skin grafting, providing an acceptable cosmetic result.
This is a giant congenital naevus on the back of a teenage boy. Excision and skin grafting of the entire lesion was undertaken.
This is the same patient as above, showing the involvement of the anterior aspect of the left arm in addition to the back.
Features
Hairy naevi present at birth, or are soon afterwards. They are classified as small (less than 1.5cm in diameter), medium (1.5cm-19.5cm) or large/giant (more than 20cm, or comprising more than 5% of body surface area). Most congenital hairy naevi are between 3 and 4cm.
Clinically, the lesion is flat, either round or oval, pigmented and covered in coarse hair. The borders can be either regular or irregular. They can be present at any site on the skin, and 5% are multiple. There is an increased risk of malignant melanoma in these patients. A large congenital hairy naevus is associated with a 8.52% risk of melanoma in the first 15 years.
Incidence
Congenital hairy naevi are present in 1% of newborns. Congenital hairy naevi over 10cm are present in 1/20,000 newborns.
Aetiology
Some families with a history of small lesions display an autosomal pattern of inheritance, with variable penetrance.
Differential Diagnosis
The diagnosis is usually very clear in these patients.
Treatment
The management is guided by the site and size of the lesions, although it is surgical. Some young children can have smaller "giant" congenital naevi removed and closed primarily, if there is sufficient tissue laxity. In the majority, the management will be more complex, involving staged excision with or without grafting (see Figure 2) and, if necessary, tissue expansion.
Laser treatment may improve the cosmetic appearance but does not eliminate the risk of malignant transformation.
