A Study of Normal Epidermal Melanocyte Distribution

Comparing the efficacy of 308-nm light-emitting diode and 308-nm excimer lamp for treating vitiligo: A randomized controlled trial

BACKGROUND

In previous studies, the 308-nm light-emitting diode (LED) has been proven safe and effective for treating vitiligo. However, direct comparisons between the 308-nm LED and 308-nm excimer lamp (308-nm MEL) for the treatment of vitiligo are lacking.

OBJECTIVE

To compare the efficacy of the 308-nm LED and 308-nm MEL for treating nonsegmental stable vitiligo.

PATIENTS AND METHODS

This randomized controlled trial was conducted between January 2018 and August 2023. Enrolled patients were randomly assigned to either the 308-nm LED or the 308-nm MEL groups, both receiving 16 treatment sessions. Adverse events that occurred during the treatment were documented.

RESULTS

In total, 269 stable vitiligo patches from 174 patients completed the study. A total of 131 lesions were included in the 308-nm LED group, and 138 lesions were included in the 308-nm MEL group. After 16 treatment sessions, 38.17% of the vitiligo patches in the 308-nm LED group achieved repigmentation of at least 50% versus 38.41% in the 308-nm MEL group. The two devices exhibited similar results in terms of efficacy for a repigmentation of at least 50% (p = .968). The incidence of adverse effects with the two phototherapy devices was comparable (p = .522).

CONCLUSIONS

Treatment of vitiligo with the 308-nm LED had a similar efficacy rate to the 308-nm MEL, and the incidence of adverse effects was comparable between the two devices.

Combined Bipolar Radiofrequency and Non-Crosslinked Hyaluronic Acid Mesotherapy Protocol to Improve Skin Appearance and Epidermal Barrier Function: A Pilot Study

BACKGROUND

Age-associated changes in epidermal hydration, pigmentation, thickness and cell renewal influence skin appearance and can lead to laxity, dryness and poor skin tone. The aim of this pilot study was to assess the synergistic effects of a new bipolar radiofrequency plus non-crosslinked hyaluronic acid (HA) mesotherapy protocol compared with radiofrequency alone on skin appearance and markers of epidermal function.

METHODS

This prospective, single-center, split-face pilot study recruited women aged 25-65 years with dryness and laxity of the facial skin defined by a trans-epidermal water loss (TEWL) value of ≥26 g/m2/h. Subjects were treated with a bipolar radiofrequency device on both sides of the face. This was immediately followed by needle hyaluronic acid (HA) treatment on one side of the face with 2.5 mL of a non-crosslinked HA. Photographic documentation, analysis of epidermal barrier function parameters, and high frequency (HF) ultrasound analysis were performed prior to treatment and at 28 days.

RESULTS

Twenty female subjects with a mean age of 46 (range 29 to 54) years and dry and lax facial skin were included. TEWL was reduced and skin hydration improved to a greater extent with the combined radiofrequency plus mesotherapy protocol compared with radiofrequency alone (-5.8% vs. +3.9% and +23.1% vs. +1.0%, respectively). The combined protocol was also associated with greater improvements in melanin (-7.5% vs. -1.5%) and erythema values (-7.2% vs. +3.0%), respectively. Ultrasound measures of epidermal thickness and epidermal density were greater after the combined protocol compared with radiofrequency alone (12.0% vs. 5.6% and 57.7% vs. 7.1%, respectively). Both treatments were well-tolerated.

CONCLUSIONS

The combined bipolar radiofrequency and HA mesotherapy protocol provided greater improvements in skin hydration, firmness and tone compared with radiofrequency alone. The combination treatment was also associated with greater epidermal thickness and density and increased keratinocyte differentiation suggesting a synergistic effect of both treatments on epidermal homeostasis and barrier function. Both treatments were well-tolerated and led to improvements in facial appearance.

Canine melanocytes: Immunohistochemical expression of melanocytic markers in different somatic areas

BACKGROUND

Melanoblasts originate in the neural crest from where they migrate to peripheral tissues and differentiate into melanocytes. Alteration during melanocyte development and life can cause different diseases, ranging from pigmentary disorders and decreased visual and auditory functions, to tumours such as melanoma. Location and phenotypical features of melanocytes have been characterised in different species, yet data on dogs are lacking.

OBJECTIVE

This study investigates the expression of melanocytic markers Melan A, PNL2, TRP1, TRP2, SOX-10 and MITF in melanocytes of selected cutaneous and mucosal surfaces of dogs.

ANIMALS

At necropsy, samples from five dogs were harvested from oral mucosa, mucocutaneous junction, eyelid, nose and haired skin (abdomen, back, pinna, head).

MATERIALS AND METHODS

Immunohistochemical and immunofluorescence analyses were performed to assess marker expression.

RESULTS

Results showed variable expression of melanocytic markers in different anatomical sites, particularly within epidermis of haired skin and dermal melanocytes. Melan A and SOX-10 were the most specific and sensitive melanocytic markers. PNL2 was less sensitive, while TRP1 and TRP2 were seldomly expressed by intraepidermal melanocytes in haired skin. MITF had a good sensitivity, yet the expression often was weak.

CONCLUSIONS AND CLINICAL RELEVANCE

Our results indicate a variable expression of melanocytic markers in different sites, suggesting the presence of subpopulations of melanocytes. These preliminary results pave the way to understanding the pathogenetic mechanisms involved in degenerative melanocytic disorders and melanoma. Furthermore, the possible different expression of melanocyte markers in different anatomical sites could influence their sensitivity and specificity when used for diagnostic purposes.

Analyzing the Spatial Randomness in the Distribution of Acquired Melanocytic Neoplasms

On the basis of the clinical impression and current knowledge, acquired melanocytic nevi and melanomas may not occur in random localizations. The goal of this study was to identify whether their distribution on the back is random and whether the location of melanoma correlates with its adjacent lesions. Therefore, patient-level and lesion-level spatial analyses were performed using the Clark‒Evans test for complete spatial randomness. A total of 311 patients with three-dimensional total body photography (average age of 40.08 [30‒49] years; male/female ratio: 128/183) with 5,108 eligible lesions in total were included in the study (mean sum of eligible lesions per patient of 16.42 [3‒199]). The patient-level analysis revealed that the distributions of acquired melanocytic neoplasms were more likely to deviate toward clustering than dispersion (average z-score of ‒0.55 [95% confidence interval = ‒0.69 to ‒0.41; P < 0.001]). The lesion-level analysis indicated a higher portion of melanomas (n = 57 of 72, 79.2% [95% confidence interval = 69.4‒88.9%]) appearing in proximity to neighboring melanocytic neoplasms than to nevi (n = 2,281 of 5,036, 45.3% [95% confidence interval = 43.9‒46.7%]). In conclusion, the nevi and melanomas' distribution on the back tends toward clustering as opposed to dispersion. Furthermore, melanomas are more likely to appear proximally to their neighboring neoplasms than to nevi. These findings may justify various oncogenic theories and improve diagnostic methodology.

Successful Repigmentation of Full-Thickness Wound Healing in Fraser’s Dolphins (Lagenodelphis hosei)

Fraser’s dolphins (Lagenodelphis hosei) exhibit the capability to restore nearly normal pigmentation after full-thickness wounding. However, the association among melanocytes, melanin and skin pigmentation during wound healing in cetaceans has yet to be addressed. Here, the number of melanocytes and the distribution of melanocytes and melanin in different-colored skin and different wound-healing stages in Fraser’s dolphins were analyzed by using Fontana–Masson staining, immunofluorescence staining and immunohistochemical staining. It was noticed that there was the highest number of melanocytes in dark skin and the lowest number of melanocytes in white skin. The appearance of functional melanocytes and full-melanized neoepidermis was observed in the early stage of wound healing in Fraser’s dolphins. Furthermore, the melanocyte number and skin pigmentation and pattern in healed wounds recovered to a similar condition of unwounded skin. This study provides fundamental knowledge of skin repigmentation in cetaceans for further research, and it will be warranted to elucidate the mechanisms of the replenishment of melanocytes and the regulation of melanocyte activity that contribute to the successful repigmentation in cetacean skin wounds.