Sebaceous Naevi
Naevus sebaceus
This shows the typical velvety, tan coloured appearance of a sebaceous naevus.
Features
Sebaceous naevi are defined as circumscribed lesions comprised predominantly of sebaceous glands.
Clinically, the lesions are well circumscribed plaques, varying between yellow and tan, and are velvety in texture. They are usually present from birth and are most commonly found on the scalp. Lesions may present in other areas, but this is relatively rare. Sebaceous naevi commonly present as a "bald patch", which is first noticed by the parents. Lesions vary between one and ten centimetres and can be oval, round or linear. Lesions usually become more raised during puberty and may become nodular as the patient progresses through adulthood.
These lesions have a small chance of undergoing malignant change. This risk has been estimated at under 5% (patient lifetime risk). The most common type of malignancy is basal cell carcinoma, although other types such as squamous cell, sebaceous and apocrine carcinomas have also been reported.
Incidence
Sebaceous naevi are found in about 0.3% of all neonates. Incidence is equal in males and females of all races.
Aetiology
Congenital lesion of unknown aetiology. Some familial cases have been reported and it has been suggested that deletion of a certain gene is responsible for the malignant predilection.
Differential Diagnosis
Verrucous epidermal naevus. Cutis aplasia.
Treatment
Where possible, excision of the lesion is indicated due to malignant potential. If the lesion is very large, then tissue expanding techniques may have to be employed. If excision is not feasible, then dermabrasion or laser removal should be considered. It should be noted that partial recurrence is likely if the lesion is not removed outright.
