Resurfacing CO2 laser treatment of linear verrucous epidermal nevus

ARTICLE

Since 1863 when Baerensprung [1] first described naevus unius lateralis, various names and classifications have been attributed to this entity because of the relatively wide range of clinical and histological presentations. Verrucous epidermal nevi can be localized, inflammatory or systemic, associating in this last case neurological, ocular, skeletal or other developmental defects.

From a histological point of view, the linear verrucous epidermal nevus (LVEN) is characterized by orthohyperkeratosis, acanthosis and papillomatosis, and can be associated with an organoid nevus [2]. A particular form, called inflammatory linear verrucous epidermal nevus (ILVEN), has been defined as a pruritic, inflammatory, persistent lesion with histopathological features resembling psoriasis [3]. Although the evolution of both entities is benign (only one case of squamous cell carcinoma reported [4]), treatment is required for cosmetic reasons. A relatively large number of therapeutic choices are available: tretinoin and 5-fluorouracil [5, 6], acitretin [7], calcipotriol [8-11], dithranol [3], podophyllin [12], CO₂ laser [13], dye laser [14], dermabrasion, cryotherapy [12]. Difficulties arise from the relatively unstable results because of a high recurrence rate of the lesions.

Five patients with ILVEN and five patients with LVEN are presented with their evolution after CO₂ laser treatment.

Materials and methods

Clinical data

1. A 5-year old female patient had had an inflammatory verrucous epidermal nevus (ILVEN) since the age of 18 months. Linear erythematosquamous lesions in the inguinal fold, on the right thigh, as well as in the perigenital and perianal region were present. She had already received treatments such as calcipotriol and topical corticosteroids without significant results.
2. An 11-year old male patient had had an inflammatory verrucous linear lesion of the left arm, forearm and hand since he was 5 years old. The diagnosis of ILVEN was confirmed histologically.
3. A 14-year old female patient presented with linear hyperkeratotic papular eruptions of the left arm, shoulder and inguinal fold, which were diagnosed as LVEN.
4. A 30-year old male patient had an LVEN of the right upper and lower limbs and trunk. The lesions were congenital. Treatment with topical corticoids and keratolytics was not effective.
5. A 34-year old male patient had an ILVEN of the left inguinal fold, scrotum, upper thigh and popliteal fold. These lesions appeared at the age of 7 and presented serious discomfort to the patient, due to the pruritus and burning sensations. Acitretine treatment did not improve the symptoms.
6. The sixth patient was a 41-year old male who had had pruritic linear erythematosquamous lesions on his left leg since the age of 10. He was treated with topical corticosteroids without acceptable cosmetic results. He complained of great discomfort because of pruritus, dryness, scaling, and severe irritation.
7. A 6-year old female patient presented with an inflammatory linear verrucous epidermal nevus of the right lower limb.
8. Since she was 3 years old, a 39-year old female of phototype IV had a LVEN of the left side of the abdomen, which appeared as a linear lesion.
9. A 7-year old girl of phototype II had a LVEN on the left inferior eyelid, of only few centimetres in size.
10. A 10-year old girl of phototype III had a LVEN of the right cheek.

In all our patients there was no clinical evidence of neurological, ocular, skeletal defects or alteration of other organs. Clinical diagnosis was confirmed by a histological examination for all patients with ILVEN.

Methods

Laser therapy

Management by superpulsed CO₂ laser was performed as follows: we started with a test treatment in order to appreciate the quality of healing and, in the case of satisfactory results, we continued two months later by removing the lesion in several sessions. The skin was prepared with an antiseptic such as Hexamidine or Betadine^®. Wet towels were placed around the treatment field. The patient was given laser safety glasses, and stainless steel eye shields were placed under the eyelids if the eyelids were to be treated. The treatment was performed with local anaesthesia with EMLA^® cream. Two children (patients no. 1 and 7) needed general anaesthesia and one week hospitalization. A Sharplan (Sharplan-ESC Medical system Ltd, Yokneam, Israël) CO₂ laser of 20 watts, with a hand piece of 200 mm, was used in the "Silk Touch™" modality (Sharplan Lasers, Inc., Allendale, New Jersey 07401, USA).

The carbon dioxide lasers have been limited by the tendency of the laser to leave behind a zone of coagulation necrosis around the treatment site, which measured up to 1 mm across. This often results in unacceptable scarring. The carbon dioxide laser emits light at 10,600 nm. This long infrared wavelength is strongly absorbed by water, which is the main component of skin. The laser light is absorbed within 20 µm of tissue. But with the conventional carbon dioxide laser, the surrounding tissue is also heated up through heat conduction away from the impact site. To confine the damage to the impact site, the laser energy must be delivered within a period of time short enough that the thermal conduction away from the impact is minimal. The desirable zone of thermal damage is 50 to 100 µm. This is small enough to successfully seal small dermal blood vessels and to maintain a bloodless field. To confine the thermal energy, pulse duration of approximately 1 msec is necessary, and enough energy must be delivered to completely vaporize the water in the target tissue. The "Silk Touch™" laser delivery system is a microprocessor controlled miniature optomechanical flashscanner compatible with most CO₂ lasers. The "Silk Touch™" consists of two orthogonally vibrating mirrors and a focusing lens. Reflections of the CO₂ laser optical beam from the mirrors cause the beam to deviate from its original direction by an angle: théta. The microprocessor-controlled mirrors are programmed to spatially and non linearly vary by théta, and generate a rapidly collapsing spiral curve on tissue with a constant tangential linear velocity, which gives a homogeneous vaporisation. Using this method, the beam is scanned in a spiral pattern so that any given spot of tissue is irradiated for less than 1 msec with an energy density of 5 to 15 J/cm² or more. The effect is as if the lasers were pulsed.

In all but patients no. 1 and 7, we chose a pulsed power of 15 watts and an exposure time of 0.45 seconds. For each region of the nevi, two passages were carried out during the same session. Between the two passes, the resulting desiccated tissue debris was wiped away with saline soaked dry gauze. Additional passes were carried out over the remaining lesions to smoothen them, but with increasing risk of complications. In cases 1 and 7, the procedure was performed using only one passage of 14 watts or less pulsed power, with 0.4 seconds exposure, because of the younger age of these patients.

Post-treatment care and follow-up

During the healing process, daily applications of vaseline and antibiotic ointments (sulfadiazin argentic FLAMMAZINE^®, or fucidic acid FUCIDINE^®) on the treated zone were performed. Follow-up was extended to a period of 2 years. Additional sessions of CO₂ laser were performed in order to eradicate the entire nevus or to treat recurrences.

Results

Patient no. 1 showed a complete recurrence of the erythematosquamous plaques one month after the first therapy session. In this case, the procedure was discontinued and our option was to prescribe local applications of calcipotriol and betametasone.

Concerning patient no. 2, four sessions of CO₂ laser were necessary in order to remove the entire lesion. Healing was achieved with a satisfactory cosmetic result (Fig. 1A, B). Only minor relapses consisting of erythematous papules were visible at the end of our observation.

Four sessions were needed for the treatment of our third patient. The healing process left a slight hyperpigmentation in this person with a skin phototype V (Fig. 2A, B).

A very good evolution was shown by the fourth patient in whom only the inguinal and axillary folds were treated.

In patient no. 5, scarring was aesthetic in the popliteal fold and on the upper thigh with a complete regression of the nevus; a few erythematous papules of 0.5 cm diameter appeared in the perigenital region for which a minor intervention was necessary. In addition, the patient experienced no further pruritus.

The sixth patient was treated only partially (Fig. 3) evolution was cosmetically satisfactory with minor desquamation of the scar and absence of pruritus.

In our seventh patient, the entire nevus was removed during one session, using a single passage. After one year, the lesion completely recurred with only a few areas of normal appearing skin.

The last two patients had entirely successfully results of the treatment, with only one passage.

Discussion

Few data are available concerning the aetiology of LVEN. The skin lesions, which are typically linear, are considered as clones of cells carrying an unknown defect. Welch et al. [15] have demonstrated the similarity of ILVEN to psoriasis from a histological and immunohistochemical point of view, while Ginarte et al. [16] individualised unilateral psoriasis by involucrin immunohistochemistry. Happle et al. [17] have recently demonstrated that CHILD nevus, classified as an epidermal nevus syndrome, is in fact an X dominant defect of cholesterol biosynthesis. Molecular biology will presumably offer clues about the pathogenesis of LVEN and ILVEN.

Numerous treatments have been suggested for epidermal nevi, each shown to be unsatisfactory. The limit of medical approaches is the great rate of relapses while surgical techniques leave permanent scars. The mechanism of action of the various substances, which have been proposed to heal epidermal nevi, is not entirely understood. Calcipotriol may exert a modulation of the production and action of cytokines and of the promotion of the epidermal differentiation in the same way as in psoriasis [11]. The chemotherapeutic agent 5-fluorouracil has an antiproliferative effect by inhibition of DNA synthesis [6]. Keratolytic agents, topical steroids, tars and tretinoin may act on some pathogenetical pathways without resolving the complex epidermal and dermal defects.

The aim of the different surgical techniques is to destroy the entire lesion and if possible without cosmetic impairment. Surgical resection is the most reliable treatment for lesions having a limited surface. Treatment by 585 nm flashlamp-pumped dye laser improved the symptoms in one case reported by Alster (1994) and the result was stable for over one year follow-up [14]. Landthalter et al. (1984) successfully treated two patients with localized verrucous nevi by argon laser [18]. Using the same method, Hohenleutner and Landhaler [19] achieved very good to acceptable results in 85% of their patients with papillomatous lesions, but failed to heal 'hard' verrucous nevi. In some of these cases, CO₂ laser was effective, whereas generally there was a tendency to hypertrophic scar formation. The same authors [20] report the complete removal by CO₂ laser, without scarring or recurrence of a widespread epidermal nevus. Ratz et al. [21] have also used this technique, which proved to be effective in 15 patients with epidermal nevi.

We present ten patients with epidermal nevi, type LVEN and ILVEN, treated by CO₂ laser. The interest of our technique is to repeat the application at low power for limiting the scarring with the CO₂ laser. We preferred to perform two passages at lower energy to try to avoid scars. Both patients with verrucous epidermal nevi had a good evolution without relapses; these relatively superficial lesions responded optimally with complete regression, leaving hyperpigmented scars but no hypertrophy.

The more profound (mid dermis) inflammatory lesions of ILVEN needed a more aggressive treatment. The underlying dermis must be removed or destroyed thus enhancing the risk of suboptimal cosmetic results. In our patients, pruritus disappeared while erythema and keratosis diminished progressively after each session of CO₂ laser treatment. Resulting wounds healed without complication. A 2-year follow-up showed that 3 patients with ILVEN experienced no significant recurrence in the treated areas. In two children (cases no. 1 and 7), in which lesions recurred perigenitally, perianally and on the lower limbs respectively, we used lower parameters of the laser (pulse duration less than 0.45 sec and energy density under or equal to 14 J/cm²). Also, we performed only one single passage on each area. In these two cases, we decided not to continue the procedure because of the scarring risk but also because anaesthesia might have been needed in these two young children if a more aggressive technique was chosen.

Article accepted on 3/5/01

CONCLUSION

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