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

Discussion

Given its benign nature, any elective treatment for DPN should balance results with potential adverse events including pain, dyspigmentation, scarring and recurrence. Patients must be clearly counselled that treatment is not medically necessary and that it will not change the natural history of this condition over time. They should be directed to providers with experience in treating skin of color.

When treating DPN, surgical modalities can require longer preparatory time for anesthesia. Bleeding can also be a problem for surgical excision or curettage, especially if multiple lesions are excised or if a patient is anticoagulated. Although a quick procedure, cryotherapy can cause significant pigmentary change, especially in skin of color. Electrodessication can result in satisfactory results, but pain is common and time should be allotted for anesthesia. Given their low costs and convenience, surgical modalities are widely available.

Laser treatment options for DPN are vast and summarized in Table 1. A major advantage to KTP or PDL lasers is the absence of pre-procedure anesthesia. The number of treatments depends on DPN size, wavelength chosen, laser settings, and operator technique. Given that the treatment zone is small, methods that help prevent damage to adjacent normal skin should be prioritized. The precise control of treatment is more difficult in surgical techniques, particularly in cryotherapy and curettage. Empirically in our practice, we preferentially use a long-pulse KTP laser with a small spot size and parallel contact cooling to precisely target DPN. Pulse-stacking is often necessary to reach a superficial whitening reaction on the lesion or until a faint "pop" is heard. Scaling and crusting of the lesions last for 5–10 days. Aftercare involves strict sun avoidance and liberal use of emollients until the treated areas have shed. The effectiveness, recovery and side effect profile of this modality has been very favorable in our hands (Figure 1). Anecdotally, patients who have experienced both KTP laser and electrodessication in the past have reported higher levels of satisfaction and more manageable "down time" with KTP laser.

Figure 1.

Patient of South Asian descent pictured before and 8 weeks after one treatment session with a long-pulse 532-nm laser. The Excel V® laser by Cutera® was used at 11 J/cm2 fluence, 3 mm spot size, 6 ms pulse duration, 10 degrees Celcius contact cooling and 1.0 Hz repetition. Pulse-stacking (3-4 pulses) was necessary to obtain the endpoint (faint popping sound or superficial whitening/scaling).

Hyperpigmentation is one of the most dreaded potential side effects when using surgical techniques to treat DPN. Postinflammatory hypo or hyperpigmentation can be mitigated with several techniques focusing on decreasing inflammation or melanin production post-procedure. There is, however, a lack of global evidence-based consensus regarding the most effective approach. Topical hydroquinone, usually in 2–4% concentration, can be used alone or in combination with tretinoin, azelaic acid or kojic acid as tolerated.[30] Topical corticosteroids, both mid to high potency, have also been reported immediately after the procedure and for short durations to prevent post-inflammatory hyperpigmentation.[31] Most importantly, strict pre and post-treatment sun avoidance should be recommended with broadspectrum ultraviolet (UV) A and UVB protection to prevent melanocyte stimulation. In the majority of studies identified in our review, post-inflammatory pigment changes in the treatment of DPN resolved within a year.

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