Treatment of molluscum contagiosum with 585 nm collagen remodeling pulsed dye laser

ARTICLE

Auteur(s) : Jean-Loïc MICHEL

Residence V Avenue; 14 place des Grenadiers-Quartier Grouchy, 42000 Saint-Étienne, France

Article accepted on 09/01/2004

The inevitable regression of molluscum contagiosum (MC) has been the major argument in favor of leaving the lesions to spontaneous involution [1]. The normal approach to MC lesions is a therapeutic minimalism. MC is a benign cutaneous disease caused by a double-stranded DNA-virus of the Poxviridae family. Clinically it consists of single or multiple dome-shaped papules with a characteristic umbilication and central plug. The lesions are most frequently located on the extremities, face, and genitalia. The disease is spread by direct skin contact, fomites, or auto-inoculation. MC generally affects children and young adults. It is usually a self-limiting disease, however the infection is often widespread and recurrent. There are a wide variety of methods for treating MC which include topical agents such as podophyllin, cantharidin, salicylic acid, tretinoin, and more recently imiquimod at 5% [1]. Destruction through electrodessication, curettage, cryotherapy, or conventional surgery is also possible. Conventional therapies are frequently ineffective and require multiple visits. Local treatment may also result in significant irritation, pain or bleeding, particularly in young children, as well as open wounds susceptible to secondary staphylococcal infections. Many of these treatments are not applicable, especially in the case of anxious children, because they are often invasive, painful, time intensive or difficult to conduct (if a stay in hospital is necessary). Flashlamp-pumped pulsed dye laser is the “gold standard” for treatment of port wine stains [2], and it is now recommended in the therapy of MC in case reports [3]. There is no evaluation of pulsed dye laser collagen remodeling (wavelength of 585 nm) as a possible therapy alternative in cases of MC. All pulsed dye lasers have revealed collagen remodeling potential. The specific features of our laser are a shorter pulse duration and lower fluence than the standard.

Material and methods

Clinical data

We treated 76 patients with cutaneous MC in a prospective study from April 2002 to September 2002 (over a period of six months), with a mean follow-up of 8 months (10 to 6 months). All patients were treated. Our purpose was to review the therapeutic response of MC to the third generation pulsed dye laser. We studied 76 cases of children with 1 to 176 MC (mean 27 MC). The female/male sex ratio was of 1.2:1 (42 girls, and 34 boys). Patients were aged from 8 months to 15 years, with a mean of 4.9 years. The group included phototypes I to IV (Fig. 1A-B). Each patient was evaluated. The following variables were extracted: age, gender, anatomic location, area involved, complications at time of the first consultation, number of treatments, previous treatment, and improvement after laser therapy. Photographs were taken under standardized conditions before and after treatment. All the lesions were measured and a number was attributed to each one.
The primary efficacy measure was the quantitative assessment of improvement in lesional volume and size. The outcome was evaluated on the number of MC present and also in size, on the following scale: 0, no improvement. 1, poor (0-25% improvement); 2, fair (26-50% improvement); 3, good (51-75%); and 4, excellent (76-100%).

Laser therapy

We used 585 nm collagen remodeling, double flashlamp excited pumped dye laser ED2000^® (manufactured by Deka© MELA Calenzano, Italy). Laser energy was delivered to the skin through an optical fiber and a lens which focused the beam. The spot size was 5 mm, the energy density (fluence J/cm²) from 2 to 4 Joules/cm² (J/cm²). Two passages were sometimes required to cause purpura. The emission modality (repetition rate) was repeated at 0.5 Hz (1 pulse per 2 second), at a short pulse duration of 250 µsec in all cases.

Results

Many children also had mild atopic dermatitis (Fig. 1A-B), and the lesions were spread over the body. Different topical applications or treatment had produced no improvement in these cases: tincture of iodine, 5% imiquimod cream, salicylic vaseline, tretinoin cream... The therapy was well tolerated. No scars or definitive pigment anomalies were observed. Hyperpigmentation occurred at some sites, however this faded after 1 to 6 months in all our cases (Fig. 1A-B). 96.3% (an excellent result) of the lesions healed after the first treatment, the remaining 3.7% after the second at two weeks interval. At a fluence from 2 to 3 J/cm² the success rate was 67% (good result) (31 patients from 8 months to 5 years), but there was no pain, and no complaints from any children, even the younger ones. At a fluence from 3.5 to 4 J/cm² (45 patients from 5 to 15 years) the result was a 98% cure of the lesions, but the pain and complaints were greater and for the younger children the treatment had to be performed under local anesthesia with lidocaïne cream (EMLA^®). Dye laser photocoagulation however, cannot protect against relapse.

Discussion

Until recently, treatment has centered on tissue destruction including curettage, cryotherapy, CO₂ laser [4], electrodesiccation, trichloracetic acid [5] and cantharadin. Recently, topical immune modulators have been used with some success [1]. These broader studies confirm the positive findings indicated in the case studies. The first report of the use of dye laser in the treatment of MC in infancy was made with a pulsed tuneable dye laser at 585 nm wavelength with a 5 mm beam width and a fluence of 6.5 J/cm² [3]. Each lesion received two pulses, and 247 lesions were treated under general anaesthetic. At the 1-month follow-up, there were only 17 remaining lesions. The other lasers with long wavelengths that are absorbed by water seem to be too painful, not sufficiently specific, or involve too great a risk of scarring [4].
Initially, a carbon dioxide laser (CO₂, wavelength: λ = 10600 nm) was employed, but this involves the risk of scarring [4] and the aerosolization of viral particles [6]. It was first proposed for the treatment of multiple and recurrent MC in human immunodeficiency virus (HIV)-positive patients with significant CD4 + T-lymphocyte depletion [5, 7]. It was also used for specific localization, such as on genitalia or vulva [8]. Multiple MC of the vulva are difficult to treat. But the carbon dioxide laser does not make treatment any easier, faster or less uncomfortable than curettage. It is used with either continuous or intermittent CO₂ laser [4]. However keloid scars could be a result of the use of CO₂ laser for MC [4]. Four out of six patients with MC have developed several keloid scars (70%). Later the indications always extended to other areas in immunodepressed patients [5, 9, 10]. With these patients it proved necessary to successfully combine other treatments with laser treatment [5, 7]. Recalcitrant MC lesions predominantly located on the face in patients with acquired immunodeficiency syndrome (AIDS), could be treated with a combination of two or more therapeutic modalities [5, 7] such as CO₂ laser, pulsed dye laser 585 nm, and 50% trichloracetic acid (TCA). The pulsed dye laser, and the TCA treated lesions resolved completely after one treatment.
For years ophthalmologists have been successfully using other types of laser for eyelid MC (responsible for conjunctivitis when MC are on the lid, as the spreading of DNA virus particles may result in viral follicular conjunctivitis) [9] such as Nd:YAG laser (λ = 1064 nm), or Argon (λ = 514 nm). These types of laser are coupled with a binocular microscope. The therapeutic effect was limited to superficial lesions because of the relatively shallow penetration of the argon laser. The Nd:Yag laser is effective for thick MC because of the deep penetration of its wavelength (λ = 1064 nm) [11]. Ophthalmologists were also the first to use a 577-nm pulsed dye laser for the treatment of MC limited to the eyelid or conjunctiva, especially in AIDS patients [6]. Hughes showed the resolution of MC following a single 585-nm pulsed dye laser treatment in five patients [12]. In patients with AIDS, widespread recurrent MC which were recalcitrant to conventional therapy, were treated with success, and without complications with a 585-nm pulsed dye laser. The pulsed dye lasers (λ = 585 nm) allow for a certain efficacy in one single session with molluscum that are recalcitrant to other extensive therapies [5, 10]. The protocol used a double pulse with a frequency of 1 Hz with a fluence of 7 to 8 J/cm² for a spot with a 3 mm diameter, and 6.8 to 7.2 J/cm² for a spot with a 5 mm diameter (3.12). 87 nodular lesions out of 88 healed after one single treatment [12]. In 20 patients, a 95.9% success was obtained after the first treatment, and in the remaining 4.1% after the second session [13]. A follow up was therefore necessary two weeks after the first treatment. Treated areas remained disease-free after 4 months [10]. There are no reports of side effects, especially with regard to scarring and pigmentation disorders [13]. A 7 mm spot size can also be used, together with a pulse duration of 0.5 to 6 msec, and a fluence of 5 to 7 J/cm². Over a 28-month period (between November 1997 and March 2000), a 585 nm pulsed dye laser was used for the treatment of molluscum contagiosum of 43 patients (14). All of the approximately 1250 lesions treated resolved, and 35% of patients (n = 15) had no new lesions after 2 treatments.

Conclusion

MC are an indication for laser therapy in all circumstances, nevertheless the final results cannot be predicted. For exposed sites with the risk of scarring, such as with lesions located on the face, in difficult cases (for example when the number of lesions is very high, curettage is also impossible) or whenever other treatment methods have failed, the pulsed dye laser for collagen remodeling is an effective, bloodless, quick, and easy therapeutic alternative for MC. It is also painless in comparison with the normal pulsed dye laser, and does not have any side effects. The collagen remodeling laser offers an additional therapeutic method for the treatment of MC, not limited to widespread and recurrent lesions.
In conclusion, the 585 nm flashlamp-pumped pulsed dye laser with very short pulse duration has proved to be an effective method with few side effects in the treatment of MC in young children. n

References

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