Exclamation Marks and Other Trichoscopic Signs of Chemotherapy-Induced Alopecia

In a 2012 study involving six chemotherapy patients without prior hair or scalp disorders, trichoscopy revealed signs of chemotherapy-induced alopecia (CIA) such as black dots, yellow dots, acute constrictions, color changes along the hair shaft, tapering hairs, and coudability hairs. Notably, exclamation mark hairs, typically associated with alopecia areata (AA), were also found in CIA patients, indicating that these trichoscopic signs are not exclusive to AA but may be a general response to hair follicle damage during the anagen phase. The study highlighted that trichoscopic features of CIA are similar to those of AA, which could lead to misdiagnosis, and that these features are a response to follicular injury rather than disease-specific. This research was among the first to document trichoscopic signs of CIA and to describe the histopathological features of CIA in humans.