Annoying, warty plaque in preteen

The Case

An 11-year-old girl has had a minimally elevated, warty plaque on her neck since birth (Figure 1). Recently, it became more elevated and itchy, annoying the patient. She complained to her mother, who then asks you to help her daughter.

Diagnosis: Linear epidermal nevus

Small focal lesions are usually isolated (Figure 2), but extensive lesions (and, rarely, localized lesions) may represent a cutaneous marker for a multisystem disorder.

CLINICAL FINDINGS

A distinctive, warty, hyperpigmented plaque composed of proliferating epidermal keratinocytes characterizes the typical linear epidermal nevus. This occurs in 0.1% to 1% of children and may involve any cutaneous and/or mucosal site, where they usually follow the lines of Blaschko.^1,2

Most linear epidermal nevi are small (a few millimeters to a few centimeters), but rarely the eruption can involve large areas of the trunk and extremities.

They may be macerated and pale at birth, subtle and minimally elevated in early childhood, and then become increasingly thickened, warty, and hyperpigmented with increasing age, especially as patients approach puberty.

Extensive lesions may be associated with epidermal nevus syndrome, with variable extracutaneous findings including developmental anomalies of the central nervous system (with seizures and mental retardation), eye, ear, skeleton, heart, and genitourinary tract and vitamin D-resistant rickets.^1-4

PATHOPHYSIOLOGY AND PATHOGENESIS

Although the cause is unknown, the distribution along the lines of Blaschko suggests genetic mosaicism. In patients with inflammatory linear epidermal nevi, keratin 10 mutations similar to that associated with congenital bullous ichthyosiform erythroderma have been identified.

Although no similar specific defects have been found in the involved skin in patients with classic linear epidermal nevi, the lesion is thought to result from variable postzygotic mutations, resulting in somatic mosaicism.

DIFFERENTIAL DIAGNOSIS

Pathology shows hyperkeratosis, variable acanthosis and papillomatosis features also seen in viral warts, seborrheic keratoses, and acanthosis nigricans.²

Clinically, linear epidermal nevi are most commonly confused with warts. However, the history of a stable congenital lesion should suggest an epidermal nevus.

TREATMENT

Treatment options include topical retinoids and peeling agents as well as destructive measures such as cryotherapy, carbon dioxide laser, and full-thickness excision.²

OUR PATIENT

A careful history, review of systems, and complete medical examination were normal, reassuring us that this child had an isolated linear epidermal nevus. Carbon dioxide laser therapy was scheduled for ablation of the lesion.

MS RAVI is a fourth-year medical student at the University of Maryland School of Medicine, Baltimore. DR COHEN, the section editor for Dermatology: What's Your Dx? is director, Pediatric Dermatology and Cutaneous Laser Center, and associate professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. The author and section editor have nothing to disclose regarding affiliation with, or financial interest in, any organization that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to allow the author and editor to focus on key teaching points. Images may also be edited or substituted for teaching purposes.

REFERENCES

1. Cohen BA. Pediatric Dermatology. Philadelphia, PA: Elsevier Mosby; 2005.

2. Brandling-Bennett HA, Morel KD. Epidermal nevi. Pediatr Clin North Am. 2010;57(5):1177-1198.

3. Happle, R. The group of epidermal nevus syndromes Part I. Well defined phenotypes. J Am Acad Derm. 2010;63(1):1-22; quiz 23-24.

4. Happle, R. The group of epidermal nevus syndromes Part II. Less well defined phenotypes. J Am Acad Derm. 2010;63(1):25-30; quiz 31-32.