Epidermal nevi may occur almost anywhere on the head, neck, legs, or trunk.6 Nevus verrucosus is a term for the localized lesions of epidermal nevi.21 Linear verrucous epidermal nevi are linear hamartomas of epidermal structures that usually appear at birth or during infancy. Linear verrucous epidermal nevi usually are found on the lower extremities and have resistance to treatment and risk of recurrence. The nevi rarely are seen on the face and very rarely involve the oral mucosa.21 Clinically, there is no erythema or pruritus. Immunohistochemical studies further help differentiate ILVEN from other noninflammatory linear epidermal nevi. The CHILD syndrome (congenital hemidysplasia with ichthyosiform erythroderma and limb defects) is characterized by segmentally distributed asymptomatic erythematous verrucous areas, associated with ipsilateral extremity defects, ranging from digital hypoplasia to agenesis of the extremity.22 Hence, ILVEN reported in association with severe extremity defects is most likely CHILD syndrome.23 An alternative acronym that has been used to describe this association is PENCIL (psoriasiform epidermal nevus with congenital ipsilateral limb defects).24 Lichen striatus usually is asymptomatic and resolves spontaneously. There also are histologic differences between ILVEN and lichen striatus.25 Linear lichen planus mainly affects children and is characterized by discrete pruritic, polygonal, violaceous papules arranged in a linear fashion, usually along an entire extremity; however, the papules also may be zosteriform.26 Linear porokeratosis also usually presents during childhood as ringlike, hypertrophic, verrucous plaques with a linear morphology, usually on a single extremity, but other parts of the body also may be involved.27 More recently, Jang et al28 reported a case of mycosis fungoides, presenting with a clinical picture of ILVEN. Nevoid basal cell carcinoma (BCC) syndrome is characterized by BCCs in both sun-exposed and nonexposed skin. The diameter of the lesions varies from 1 to 10 mm and commonly involves the face, back, and chest. Features such as odontogenic cysts, palmar and plantar pitting, and facial milia may be associated. Basaloid follicular hamartoma, also known as linear unilateral basal cell nevus with comedones, may present as a unilateral linear lesion.29 In its early stages, the lesion shows hypopigmented smooth or striaelike areas, which later may develop darker-pigmented papules and tumors with or without ulceration. Of note, it may be histologically indistinguishable from the infundibulocystic type of BCC.29 The most widely applied medical treatments for ILVEN have been intralesional corticosteroids or potent topical corticosteroids, the latter often with occlusion.30 However, the clinical appearance and associated intense pruritus usually are refractory to treatment. Topical calcipotriol has been reported to provide some relief in some patients,31 but it is not recommended in children because of limited clinical safety data. A recent case report noted improvement of pruritus in ILVEN with topical pimecrolimus cream.32 Dithranol has been used with success in one case report,33 but this has been interpreted as an antipsoriatic effect in ILVEN with superimposed psoriasis.34 Other therapeutic choices reported in the literature include topical tretinoin combined with 5-fluorouracil,35 and acitretin.36 Destructive therapies, such as the application of liquid nitrogen, electrodesiccation, ablative laser and dermabrasion, have all been equally disappointing.37 Of note, case reports have shown efficacy of CO238 and pulsed dye laser treatment.39
Conclusion
ILVEN may be an isolated finding or may be associated with other abnormalities. Most patients pre-sent in infancy or early childhood. The diagnosis may sometimes be difficult and necessitate biopsy and advanced immunohistochemical analysis. Most lesions do not persist and spontaneously resolve by adulthood.40 The management usually is only symptomatic and often unsatisfactory.