An epidermal nevus is a non cancerous overgrowth of the epidermis. Human skin has three layers, epidermis is the outermost layer. At least in 50 percent of cases the lesion develops at birth or may develop later usually in the first year of infancy. The lesions can vary in size and number. Epidermal nevus is rare and occurs 1 out of 1000 people according to an estimate. Epidermal nevi are of variety of types depending on type of epidermal cell. Among them the commonest is keratinocytic epidermal nevi.
Epidermis is composed of keratinocyte cells, hair follicle, sweat glands.Epidermal nevi may also involve these types of cells. The nevi comprising from such epidermal cells is called organoid epidermal nevi. Epidermal nevus is often associated with other developmental abnormalities of eye, neurological, urinary and cardiovascular system.
Causes Of Epidermal Nevus Syndrome
Each individual has two copies of genes, one each from mother and father. According to some, it is believed that there are two varieties of skin cells. It may contain either the genes from mothers side or from fathers side. If in any case one side of skin cell is abnormal it will result in formation of epidermal nevus, where the local lesion becomes thick.Although genetically oriented, epidermal nevi usually affect not more than one person in the family. Researchers have found genes mutation in epidermal nevi.
Most epidermal nevi are sporadic in development, but sometimes familial lineage is also seen. Epidermal nevus originates from some defect in the ectoderm which is the first stage of skin cell formation during the fetal development. Epidermal nevi are linear and develop along the line of Blashko. This line which is not visible on skin is believed to follow the path along which the skin cells start developing during the fetal stage.
Symptoms Of Epidermal Nevus Syndrome
Epidermal nevus can be localized in one area of skin or may be diffused and spread in large areas of body. In majority of cases epidermal nevus is congenital meaning from the birth. However, sometime the lesions may develop later after birth mostly in first year of life. Rarely the lesions may appear later in childhood. Most epidermal nevi form on torso or in hands and legs.
The lesions are tanned colored flat patches on skin surface. In some cases the patch is raised and feels velvety. With aging the nevus becomes thick and rough. Its color becomes dark brown and more often the nevus appears as a warty growth. The characteristic feature of epidermal nevus is its spread in line which is known as line of Blaschko.
The lesions are one sided. When there are multiple nevi, there may be associated congenital abnormality of other organs such as in nervous system, eyes, bones, heart, etc. When the nevus is associated with abnormality of other system, the condition is referred as epidermal nevus syndrome.
Treatment Options For Epidermal Nevus
Epidermal nevus is harmless as it is a benign lesion. However, most people take treatment for cosmetic concern. Especially when the skin lesions are present on the exposed part of the body in large number or the lesion is big in size. When present in groin or armpits it may become painful or the skin may get infected because of repeated friction. Applying topical steroid cream may be found useful in some cases. In case of widespread epidermal nevus all over the body, oral retinoid medicines have been found to be effective.
The treatment of choice in most cases is to remove the nevus surgically. Especially, if there are few or solitary nevus. Besides surgical excision, other modes of effective treatment are laser surgery, dermabrasion, and cryosurgery. The most often treatment choice is laser therapy because there is less risk of scar formation after the nevus disappears. Recurrence can occur after few months or years with any approach of treatment.