Telogen Alopecia Induced by UV Rays

The document reports on a form of telogen alopecia induced by UV rays, observed in patients treated with minoxidil and tretinoin for androgenetic alopecia. The study found that some patients developed sunburns on their scalps after sun exposure, which was exacerbated by the scalp irritation caused by tretinoin. This led to a temporary cessation of treatment for 15 to 20 days. Subsequently, these patients experienced increased hair loss 3 to 4 months later, initially thought to be due to stopping the medication. However, further investigation revealed that the hair loss was actually a result of the UV-induced sunburn. This was confirmed by a case of a young woman who experienced significant hair loss after a severe sunburn on her scalp, and a review of files that showed similar alopecia in 17 male patients treated with minoxidil and tretinoin, as well as 5 healthy women treated with minoxidil alone. The clinical features included increased frontovertical hair shedding and a trichogram showing at least 20% more telogen hairs. The authors conclude that UV ray-induced telogen effluvium is a new form of hair loss that should be considered when classifying alopecias.