• #2-5. Mottled hypopigmentation from laser toning in the treatment of melasma : histopathologic characteristics and management



    Along with repigmentation of hypopigmented lesion, melanin pigments reduction on nearby hyperpigmented area could be the other main goal in the treatment of LTID. This is similar to the treatment of melasma. Most basic and traditional treatments such as topical bleaching agents,2 glycolic acid peel25 have been also used for treating melasma with LTID. Ryu et al.25 reported tretinoin improved LTID successfully. They suggested its potential therapeutic effects in both hyperpigmentation and hypopigmentation.


    In previous reports, even after the onset of hypopigmentation, some authors continued LT or 578 nm copper bromide laser as the treatment of melasma for the purpose of decreasing the contrast ratio.6,23 Although controversy exists over continuing treatment after hypopigmentation develops, we believe that it is generally good practice to discontinue LT and other laser treatments promptly once hypopigmentation develops. As the occurrence of hypopigmentation is closely associated with patient factors and treatment techniques, continuing laser therapy thoughtlessly can worsen the coloring, size, and number of hypopigmented lesions. Therefore, once the LTID arise, we recommend temporary discontinuance of all laser treatments including LT. If this is followed by stabilization of hypopigmentation without further progression, LT treatment with much gentler parameters than those used previously can be resumed. It goes without saying that areas of hypopigmentation should be avoided. What we mean by ‘gentler LT therapy’ is a treatment method with a lower fluence, less passes, longer treatment intervals, and closer monitoring any signs of complications compared to those used in the previous treatment.


    Besides, fractional toning can be one of the anticipated treatment options. The 1,064 nm QS Nd:YAG fractional laser may allow continued treatment of melasma while preventing further development of hypopigmentation. Especially, fractional laser toning using a spot size of 0.2 mm may only cause very small hypopigmented lesions, making them less visible and even giving the impression of melasma improvement. For these reasons, it can be considered a useful treatment tool in patients who have already developed hypopigmentation.


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     As discussed above, much more scientific evidence is needed to establish therapeutic modalities, outcomes and prognosis in the treatment of LTID. Due to such lack of evidence, it is very difficult to predict the course of LTID with or without treatment. Therefore, we cannot stress enough how important ‘prevention’ is. LT should be carried out with caution and in consideration of the patient’s individual skin characteristics and clinical features of melasma. As we have emphasized in the previous article, one should always try to avoid aggressive parameters. The patient should be closely monitored for any signs of complications after each treatment session. We believe that early discovery of complications and immediate discontinuation of laser therapy are the most important prognostic factors in LTID. Other choices including phototherapy, fractional lasers can be tried with caution and the most appropriate modality should be chosen in consideration of patient characteristics and clinical conditions.


    -To be continued

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