Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare entity that presents with linear and pruritic psoriasiform plaques and most commonly occurs during childhood. It represents a dysregulation of keratinocytes exhibiting genetic mosaicism.1,2 Epidermal nevi may derive from keratinocytic, follicular, sebaceous, apocrine, or eccrine origin. Inflammatory linear verrucous epidermal nevus is classified under the keratinocytic type of epidermal nevus and represents approximately 6% of all epidermal nevi.3 The condition presents as erythematous and verrucous plaques along the lines of Blaschko.2,4 There is a predilection for the legs, and girls are 4 times more commonly affected than boys.1 Cases of ILVEN are predominantly sporadic, though rare familial cases have been reported.4
Inflammatory linear verrucous epidermal nevus is notoriously refractory to treatment. First-line therapies include topical agents such as corticosteroids, calcipotriol, retinoids, and 5-fluorouracil.3,4 Other treatments include intralesional corticosteroids, cryotherapy, electrodesiccation and curettage, and surgical excision.3 Several case reports have shown promising results using the pulsed dye and ablative CO2 lasers.5-8
Case Report
An otherwise healthy 20-year-old woman presented with dry, pruritic, red lesions on the right leg that had been present and stable since she was an infant (2 weeks of age). Her medical history included acne vulgaris, but she denied any personal or family history of psoriasis as well as any arthralgia or arthritis. Physical examination revealed discrete, oval, hyperkeratotic, scaly, red plaques on the lateral right leg with a larger hyperkeratotic, linear, red plaque extending from the right popliteal fossa to the posterior thigh (Figure 1A). The nails, scalp, buttocks, and upper extremities were unaffected. Bacterial culture of the right leg demonstrated Staphylococcus aureus colonization. Biopsy of the right popliteal fossa showed psoriasiform dermatitis with psoriasiform hyperplasia, a slightly verruciform surface, broad zones of superficial pallor, and parakeratosis with conspicuous colonies of bacteria (Figure 2).
Figure 1. Inflammatory linear verrucous epidermal nevus lesions demonstrating discrete, hyperkeratotic, scaly, red plaques on the lateral right leg before (A) and after 18 treatment sessions with the 308-nm excimer laser (B). Improvement in hyperkeratotic scale and mild improvement in erythema was demonstrated.
Figure 2. Uneven psoriasiform hyperplasia with a slightly verruciform surface, broad zones of superficial pallor, parakeratosis, focal hypergranulosis, vascular ectasia, and superficial perivascular and interstitial infiltrate of lymphocytes and plasma cells (H&E, original magnification ×10).
Following the positive bacterial culture, the patient was treated with a short course of oral doxycycline, which did not alter the clinical appearance of the lesions or improve symptoms of pruritus. Pruritus improved moderately with topical corticosteroid treatment, but clinically the lesions appeared unchanged. The plaque on the superior right leg was treated with a superpulsed CO2 laser and the plaque on the inferior right leg was treated with a fractional CO2 laser, both with minimal improvement.
Because of the clinical and histopathologic similarities of the patient's lesions to psoriasis, a trial of the UV 308-nm excimer laser was initiated. Following initial test spots, she completed a total of 18 treatments to all lesions with noticeable clinical improvement (Figure 1B). Initially, the patient returned for treatment biweekly for approximately 5 weeks with 2 small spots being targeted at each session, with an average surface area of approximately 16 cm2. She was started at 225 mJ/cm2 with 25% increases at each session and ultimately reached up to 1676 mJ/cm2 at the end of the 10 sessions. She tolerated the procedure well with some minor blistering. Treatment was deferred for 3 months due to the patient's schedule, then biweekly treatments resumed for 4 weeks, totaling 8 more sessions. At that time, all lesions on the right leg were targeted, with an average surface area of approximately 100 cm2. The laser settings were initiated at 225 mJ/cm2 with 20% increases at each session and ultimately reached 560 mJ/cm2. The treatment was well tolerated throughout; however, the patient initially reported residual pruritus. The plaques continued to improve, and most notably, there was thinning of the hyperkeratotic scale of the plaques in addition to decreased erythema and complete resolution of pruritus. Ultimately, treatment was discontinued because of lack of insurance coverage and financial burden. The patient was lost to follow-up.