Three Cases of Radiation-induced Temporary Alopecia with Hair Microscopic Examination: "Coudability Hair" Might Not be Specific for Alopecia Areata.

Endovascular interventional procedures are widely used for the treatment of intracranial vascular lesions. However, they sometimes produce reversible alopecia, known as radiation-induced temporary alopecia, depending on the radiation dose. Radiation-induced temporary alopecia manifested as rectangular alopecic patches without signs of inflammation, reflects damage to the keratinocytes in the hair matrix of anagen hair follicles, due to the sensitivity of these cells to radiation. The characteristics of radiation-induced temporary alopecia are similar to those of alopecia areata as follows: (1) clinical findings of well-defined alopecic patches and (2) dermoscopic findings of yellow dots, black dots, and short vellus hairs. The two conditions can be distinguished according to whether there is any history of endovascular interventional procedures, and by the shapes of the lesions and the inflammation status on histopathologic examination. A hair microscopic examination is a useful diagnostic tool in patients with hair loss disease, but the features of radiation-induced temporary alopecia have not been well described. Here, we report three cases of radiation-induced temporary alopecia preceded by endovascular procedures, including stent insertion and coil embolization.