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An epidermal nevus is a congenital condition in which there is a benign overgrowth of the embryonal ectoderm in the skin, leading to a cutaneous warty or smooth raised lesion.
It is present at birth, though it may manifest much later, in childhood. This may be up to several centimeters in length, but may cover a much larger area in some cases.
The nevus may be formed of keratinocytes, forming a non-organoid epidermal nevus. It may be organoid, in which case it is made up of other epidermal components such as sebaceous cells, apocrine cells, eccrine cells, or follicular cells (from sebaceous glands, sweat glands, and hair follicles in the skin). The most common type is the keratinocytic or verrucous epidermal nevus, which presents at birth.
In a third of affected individuals, other organs are also affected. In such cases, an epidermal nevus syndrome is present, with sporadic presentation, comprising neurological, skeletal, ocular, and cutaneous defects caused by congenital abnormality of the ectoderm.
No universally accepted treatment regimens have been worked out for epidermal nevi. Both the type of the lesion and the possibility of the epidermal nevus syndromes being present make the choice of treatment a perplexing one. Both medical and surgical treatments have been used.
These potent anti-inflammatory agents have been used both topically, with the help of an occlusive bandage, or by intralesional injection, with mixed results.
This vitamin A derivative has been used topically with some evidence of at least partial efficacy.
Oral retinoids have an anti-proliferative action on the epidermis, but their use must be life-long to prevent recurrence.
Topical application of calcipotriol has been found to help in cases of inflammatory linear verrucous epidermal nevus (ILVEN).
Other agents which were found to be of use include tacrolimus, fluocinonide, and 5-fluorouracil.
Surgical excision
This is the gold standard for the treatment of small epidermal nevi, and is usually adopted for cosmetic reasons. It may not be possible if the nevus originates too deeply. Recurrence has been known to happen in some cases. Scarring is a significant and inevitable limitation of this modality.
Superficial treatments
Other modes of ablating superficial layers of the skin include cryosurgery, dermabrasion, electrosurgery, and laser surgery. In some locations, moreover, the use of surgery is contraindicated.
Dermabrasion is usually too superficial to provide a permanent cure, as recurrence occurs from the hamartomatous residual cells. If it is done too deeply, however, the skin heals leaving behind thick unsightly scars.
Cryosurgery is associated with slowness of healing, a high risk of infection, swelling, and post-operative discoloration around the site of treatment.
Laser treatment usually depends on the use of carbon dioxide, the long-pulsed Nd:YAG laser, and the dye laser. There may be a recurrence of the lesion within a year in almost a fourth of patients. However, by any method of removal used so far, recurrences are known to occur, whether the period of relief is measured by months or by years.
Surgical and medical methods may be used in combination, such as in shave excision followed by a phenol peeling, to achieve deeper removal without the scar of a surgical excision.
Any epidermal nevus which shows a significant change suspicious of malignancy, such as ulceration or swelling, should be excised with a conservative margin and the specimen sent for histopathological examination.
If the patient has an epidermal nevus syndrome, specific treatment must be given based upon the defects present. This includes anti-seizure medications, surgical correction of skeletal anomalies according to current working guidelines, and removal of cysts or other defects in the brain which may precipitate epilepsy.
Physiotherapy, mental rehabilitation, and occupational therapy for the mentally challenged, and symptomatic therapies, are all required. Genetic counseling is important to reassure patients and their families that the mutation is somatic and sporadic, without the risk of transmission.