## 4 Discussion  
We may define hyperpigmentations as the storage of a pigment such as melanin into the skin layers. Q-Switched lasers use the photomechanical effect to destroy the targeted chromophores, having no or minimal photothermal effect on surrounding tissues [13; 14; 15]. Only hyperpigmentations not associated with the risk of degeneration in malignancies should be treated with lasers; other hypermelanotic lesions, such as dysplastic nevi, should be handled with surgery. Lesions approachable by laser therapy may be divided into epidermal pigmented lesions (such as lentigo simplex, ephelides, cafe au lait spots, linear hypermelanosis, Spilus, and Becker spots) and dermal pigmented lesions (such as melasma, post-inflammatory hyperpigmentation, acquired and congenital dermal melanocytosis) [16; 17; 18]. Due to the superficial distribution of melanin, all epidermal melanoses respond better to the 532 nm wavelength [19; 20]. Only cafe au lait spots seem to have a better response at 1064 nm. Although the 1064 wavelength usually gives better results to dermal melanosis, the outcome remains controversial in melasma, probably related to its poorly understood etiology [21; 22; 23]. Acquired hyperpigmentations seem to reach better cosmetic outcomes than their congenital ones [24; 25; 26]. Our study's findings suggest a significant efficacy of lasers in lentigo and other superficial lesions and lower phototypes. The patients reported outstanding satisfaction levels, and a very low number of treatment sessions was necessary, confirming the picosecond pulsed laser as very effective as already reported by other studies in the medical literature [18; 27; 28; 29]. The limitations of our study include the small number of recruited patients, the lack of digital skin analysis devices (that could have better-quantified melanoses' removal), and histologic analysis. Our study confirms the results obtained with other picosecond pulse Q-switched lasers, showing outstanding results for hyperpigmentation management. In our cohort of participants, lighter phototypes and superficial melanosis responded better to the treatment. In comparison, darker phototypes and deeper lesions responded worse to laser therapy, and an augmented number of sessions was necessary. Patients signaled only minor side effects such as superficial crusting. A randomized trial comparing nanosecond and picosecond pulsed range Q-switched lasers with a significant number of patients will be necessary to confirm this study's findings. Although, our data broadly agree with previous, both simulated and in vivo, studies that suggest the picosecond laser to be the more effective modality, as lower pulse duration should improve results by selectively targeting the melanin in the hyperpigmented lesions [30; 31]. Conceptualization, G.C. and L.B. ; methodology, F.T. ; validation, S.P.N. and M.S. ; formal analysis, E.Z. ; investigation, L.B. writing--original draft preparation, G.C. and M.S. ; writing--review and editing, S.P.N. and L.B. ; supervision, N.C.; All authors have read and agreed to the published version of the manuscript. This research received no external funding. The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Institutional Review Board of Calabria centro (protocol code 000373/2019; date of approval 17 December 2019). \begin{table}
\begin{tabular}{c c} \hline \hline
**Type of Treated Clinical Melanoses** & **Number of Patients** \\ \hline Solar lentigo & 25 \\ \hline Ephelides & 5 \\ \hline Cafe au lait spots & 3 \\ \hline Linear hypermelanosis & 1 \\ \hline Melasma & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Types of melanoses removed. **Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study. Written informed consent has been obtained from the patient(s) to publish this paper. **Data Availability Statement:** Data are available from the corresponding author upon reasonable request. **Conflicts of Interest:** The authors declare no conflict of interest.