Dear Editor:

I have read the paper “A Study of Normal Epidermal Melanocyte Distribution” by Sun et al.1in the International Journal of Dermatology and Venereology (October 2020). I would like to congratulate the authors on their interesting findings. It is intriguing to learn that the melanocyte density differs among specific areas of the body and that the skin thickness is not associated with the melanocyte density.

I am interested to know whether these data are similar between ethnic groups inChina and ethnic groups across the world. Populations near the equator would be expected to have a higher melanocyte density than populations farther away from the equator. Considering that 55 different ethnic groups are present in China, it would be interesting to determinewhether any differences existamong these groups.One other variable worth testing would be the effect on smog on melanocyte density. Do populations in China living outside the city of Beijing have the same melanocyte density as those living within the city? This could also have implications internationally because smog is an issue in many industrial centers.

I would like to thank the authors again for their contribution. I believe that this research will help the medical community understand melanoma and its underlying pathogenesis.

Mitchell Brady

OMS 3 Idaho College of Osteopathic Medicine,Meridian, ID 83642, USA

E-mail: mbrady@s.idahocom.org.