Elective Treatment of Dermatosis Papulosa Nigra

A Review of Treatment Modalities

Mimi Tran, MD; Vincent Richer, MD, FRCPC, FAAD

Disclosures

Skin Therapy Letter. 2020;25(4):1-5. 

In This Article

Treatment Modalities of DPN: Advantages, Disadvantages and Adverse Events

Scissor Excision

The treatment of DPN using simple scissor excision is overall well tolerated, with bleeding, erythema, and edema being the most common acute adverse events.[11] Pedunculated lesions of DPN are the most amenable to scissor excision.[12] Common tools include fine curved scissors, used with or without local anesthesia, and post-procedure wound care consists of petrolatum or topical antibiotic application. Although there are few studies reporting outcomes for scissor excision, we suspect adverse events to be similar with other surgical excisions of epidermal lesions including pain, hemorrhage, dyspigmentation, scar, and recurrence.

Cryotherapy

Cryotherapy has the advantage of being inexpensive and fast, with minimal pre-procedure preparation.[13] However, limited peer-reviewed studies on the success of DPN treatment with cryosurgery have been published. Depending on the depth of the lesion and provider technique, number of treatments and freeze-thaw cycles may vary.[14,15] The chief concern with this modality in patients with skin of color is hypopigmentation, caused by damage to melanocytes in underlying or surrounding healthy skin. As such, this modality should be used with extreme caution.[16]

Curettage

Curettage is another surgical option for epidermal tumors. As with cryotherapy, the cost is minimal. Different size curettes can be used depending on size of DPN. Anesthesia is typically administered prior to the procedure, however, studies have reported treatment without anesthesia with minimal adverse outcomes.[15] Kauh et al. described 20 cases treated with light abrasive curettage without local anesthesia as an effective treatment for DPN with no scarring.[15] In one study, curettage had higher mean clearance rates for the treatment of DPN compared to electrodessication and pulsed-dye laser, although the rates were not statistically significant.[17] The main concern with curettage is risk of pigment changes and cosmetically unacceptable scars.

Electrodessication

Electrodessication is routinely used in the treatment of epidermal tumors including seborrheic keratoses, warts, acrochordons, and DPN. Wall-mounted electrosurgical units are most commonly used for DPN.[17,18] The voltage is set lower and titrated up, with studies showing an average setting of 0.6–1.0 W. Pain is a common complaint during procedures and thus local or topical anesthesia can be used prior to treatment. Kundu et al. showed that DPN improvement was comparable between electrodessication and KTP laser.[19] However, patients preferred KTP laser due to comfort.[19] Notably, in this study, no anesthesia was provided to the electrodessication group. Garcia et al. demonstrated that electrodessication was the most preferred modality for cosmetic outcomes compared to PDL and curettage for treating DPN, and showed comparable treatment outcomes, although findings were not statistically different.[17]

532-nm Potassium-titanyl-phosphate Laser and 532-nm Diode Lasers

At 532-nm, the long-pulse KTP laser is most commonly used to treat vascular skin lesions. The KTP laser is a Nd:YAG laser whose beam is directed through a non-linear frequency-doubling potassium-titanyl-phosphate (or most recently, lithium borate) crystal, producing a beam in the green visible light spectrum.[20] Like the PDL, the KTP can also be absorbed by melanin and thus can be used in pigmented lesions, including solar lentigines.[21] There are two splitface splitface studies highlighting KTP laser as a treatment for DPN. Compared to electrodessication, Kundu et al.[19] showed that 75% of patients (n=14) displayed 76–100% improvement using 1 mm spot, 10 ms pulse at 15 J/cm2. The efficacy was comparable to electrodessication. Joshi et al.[22] performed a similar study with 15 patients showing comparable efficacy between KTP laser and electrodessication, but approaching significance in favor of KTP laser. In both studies, patients rated KTP laser as less painful and more favorable compared to electrodessication. Similar findings showed excellent treatment response with mild postinflammatory hypopigmentation using the 532-nm diode laser with settings of 700 to 1000 microns spot size, 8–16 J/cm2 settings to treat DPN.[23,24]

Pulsed Dye Laser

With a wavelength of 585-nm, PDL has a high affinity for oxyhemoglobin and thus is used for many vascular skin conditions. Large structures containing melanin can also absorb PDL energy, particularly if used with a longer pulse duration.[25] Using a 7 mm spot size, 10 J/cm2 and 10 ms pulse duration, one treatment using PDL showed similar treatment outcomes compared to curettage and electrodessication.[17] Although not significantly different, findings did show that PDL was more painful. Favorable improvement and outcomes were achieved with 7 mm spot size, 8–9.5 J/cm2 with 10 ms pulse duration PDL in one case report, but required 2–6 sessions to achieve these results.[26]

Q-switched and Picosecond Lasers

Though not formally reported in the scientific literature, Q-switched and picosecond range lasers with wavelengths targeting pigment such as 532-nm, 694-nm, 755-nm and 1064-nm are used in clinical practice to treat DPN. It is believed that due to the short pulse duration resulting in less photothermal and more photomechanical effects, picosecond lasers may reduce the risk of postinflammatory hyperpigmentation.

Neodymium-doped Yttrium Aluminium Garnet laser

Two patients with DPN achieved excellent results in one treatment with the long-pulsed Nd-YAG at 3 mm spot size, 145–155 J/cm2, and 20 ms pulse duration.[12] The patients required no anesthesia and reported minimal discomfort.

Resurfacing Lasers: Erbium-doped 1550-nm Fractionated Laser

Non-ablative resurfacing has become the treatment of choice for a broad range of aesthetic indications. Non-ablative water-targeting lasers allow for shorter downtime and less complications. One case report showed a successful treatment of DPN using a 1550-nm wavelength erbium-doped laser at 60–70 mJ, treatment level 7, 20% coverage, 2.42–2.94 kJ total energy, with 8–10 passes over 3 treatments.[27] Topical anesthetic was used prior to treatment.

Resurfacing Lasers: Carbon dioxide (CO2) Laser

Ablative lasers are another well-established option to treat epidermal tumors. Carbon dioxide laser is one of the oldest gas medium ablative laser devices and there is significant clinical experience in treating a variety of conditions including nevi, verruca, keloids, and acne scarring. A retrospective study showed high satisfaction of patients who received CO2 laser treatment on DPN with no post-procedural complications, although there was a 28% recurrence rate.[28] Bruscino et al.[29] used spot size of 0.7 mm, 0.5–0.7 W, and 10 Hz to treat 5 female patients with DPN, resulting in excellent response and no recurrence.

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