epidermal nevi

How would you treat these verrucous papules?

Mr Tolkachjov is a fourth-year medical student at The University of Tennessee Health Science Center in Memphis. Dr Wilson is associate professor and associate director of the residency program in the department of dermatology at University of Virginia School of Medicine in Charlottesville.

Kirk Barber, MD, FRCPC- Series Editor: Dr Barber is a consultant dermatologist at Alberta Children's Hospital and clinical associate professor of medicine and community health sciences at the University of Calgary in Alberta.  

nevi

Case: A 2-year-old boy has had a cluster of asymptomatic, pink to tan, verrucous papules on his right dorsal foot since 6 months of age. The lesion has slowly enlarged. The child has no other lesions and no known medical conditions. The parents have tried using duct tape for empirical treatment of a wart, without a response.

What can you tell the parents that will spare this child more duct tape applications?

(Answer on next page.)

Answer: Verrucous epidermal nevi require no treatment unless cosmetically
unacceptable; in which case, excision is the preferred approach.

Although the lesion did have the warty appearance of verruca vulgaris, verrucous epidermal nevus must also be considered in the differential diagnosis of such a lesion. A shave biopsy was performed to confirm the diagnosis, and spare the 2-year-old boy from unnecessary painful wart treatments. The histopathology showed hyperkeratosis, acanthosis, and papillomatosis, without evidence of koilocytosis or other viral changes. These findings are consistent with a verrucous epidermal nevus. Typically, this diagnosis is clinical; however, such lesions usually have a linear arrangement of papules (see Figure) rather than a cluster, as in this young boy.

The estimated incidence of epidermal nevi is 1 per 1000 live births. Most lesions present at birth or in infancy; however, they may appear in adolescence or early adulthood. Epidermal nevi tend to grow during early childhood and stabilize during adolescence. Although the classic linear epidermal nevi can appear anywhere on the skin surface, they most commonly affect the extremities.

Epidermal nevi that present on the face and scalp in association with neurological abnormalities, such as seizures and cognitive deficits, would prompt the differential diagnosis of epidermal nevus syndrome. This syndrome encompasses several CNS, skeletal, ocular, and genitourinary phenotypic abnormalities associated with epidermal nevi. Malignant transformation to basal cell or squamous cell carcinomas is a rare occurrence reported in patients of advanced age. However, the infrequency of such neoplastic change allows for observation as the standard of care unless diagnosis is in question.

Removal of epidermal nevi is unnecessary unless the lesions are cosmetically unacceptable or the diagnosis is in question. If a decision is made to remove the lesion, the preferred approach is excision to at least the deep dermis. Carbon dioxide laser also has been used successfully in the treatment of epidermal nevi. Cryotherapy and electrofulguration can be tried; however, the lesions may recur as a result of insufficient depth of destruction.