Causes and risk factors
The exact cause is still not known. Studies have shown that the genetic factors are responsible for this condition. Mutation in pluripotent cells during embryogenesis results in sebaceous nevus. Abnormality in the PTCH gene has been detected.
Clinical presentation
Sebaceous nevus is seen as solitary hairless overgrowth and thickened skin patch particularly on the scalp. It has a velvety orange and yellow color. Other areas like the head and the neck can also be affected. The appearance of lesion varies as per the stages of life. At birth, hairless single lesion which is round or linear in shape is seen. It is yellowish pink or orange in color resembling a velvet. The common site affected is the scalp, particularly the vertex or face. As the age advances, in adulthood the lesion becomes verrucous and the size can increase, ranging from 1 cm to more than 10 cm. During the latter part of life, the tumor is formed. The patient does not suffer from any subjective complaints; however, it does hamper the cosmetic appearance.
Investigations
Diagnosis is done on the basis of symptoms narrated by the patient and the examination carried out by the dermatologist. Clinical examination itself is diagnostic. Histological examination along with skin biopsy can be done.
Treatment:
Full-thickness excision or laser therapy is the choice of treatment. Photodynamic therapy can be used.
