Telogen Effluvium: The Debate on Catagen and Hair Shedding Mechanisms

In the correspondence regarding telogen effluvium, Drs. David Weedon and Geoffrey Strutton criticized John J. Headington's article for perpetuating the concept of telogen effluvium, arguing that it obscures the importance of catagen in the hair cycle. They suggested that apoptosis, influenced by genes such as bc1-2, myc, p53, and APO-1/Fas, is a key mechanism in catagen and is pivotal for hair shedding. In response, Headington clarified that while catagen has no detectable clinical signs, it is important histologically for diagnosing some alopecias. He acknowledged that the idea of club hair shedding as an active biological process is unsubstantiated by experimental studies, but based on his examination of over 1,000 scalp biopsy specimens, he could not confirm a passive mechanism for hair shedding. The exchange highlights a debate on the significance of catagen and the mechanisms of hair shedding in the context of telogen effluvium.