Anagen Effluvium after Neurointerventional Radiation: Trichoscopy as a Diagnostic Ally

Anagen effluvium is a nonscarring alopecia caused by various insults, most commonly associated with chemotherapeutic agents. Approximately 90% of scalp hairs are anagen follicles, which is the hair growth phase of active division and proliferation that lasts from 2 to 6 years [1]. Anagen follicles are very sensitive to high doses of radiation, which causes damage in the actively dividing cells [1, 2]. Unlike chemotherapy or radiotherapy induced anagen effluvium, intracranial endovascular procedures produce a well-demarcated alopecic patch consistent with the treatment area [3] (Fig. 1).

Radiation-induced anagen effluvium after neurointerventional procedures has been reported with increasing frequency. Nonetheless, its clinical characteristics and trichoscopic features are nonspecific, thus further research could aid in the diagnosis. Since minimally invasive procedures with radiation are performed more frequently in the field of neurointerventional surgery, dermatologists should include radiation-induced temporary alopecia [4] in the differential diagnosis of nonscarring alopecias.

Herein, we conducted a comprehensive search of current literature from PubMed and SCOPUS search engines, including case series and case reports that described trichoscopic findings of patients with radiation-induced temporary alopecia. A total of 25 research outputs were found, including textbooks, book chapters, case reports, case series, original articles, and reviews. We then decided to include 8 articles describing neurointerventional radiation procedures, as well as 3 personal cases from our clinic.

Current literature regarding clinical and trichoscopic findings in patients who developed an alopecic patch after neurointerventional radiation exposure, including our cases is shown in Table 1. A total of 22 cases including our 3 cases have been reported on the literature up to this date. Demographic and clinical characteristics are shown in Table 2. Women represent 63.6% of cases, men 36.4%, with a wide age-group, from 4- to 70-year-old patients, 63.6% between 20 and 50 years, 9% <20 years, and 36% 50-year-old patients or older. The most common trichoscopic findings reported (shown in Table 3; Fig. 2) were yellow dots (50%), black dots (50%), short vellus hairs (41%), and absence of exclamation mark hairs (23%); additional trichoscopic findings were coiled hairs, peripilar sign, lack of terminal hairs, broken hairs, dystrophic hair roots, white dots and blue-gray dots in a target-like pattern [2, 3, 9, 10]. The location of the alopecic patch corresponded to the area that received radiation during the endovascular procedure (Fig. 3). The time from the procedure to the onset of alopecia (Fig. 4) ranged between 1 and 8 weeks, with an average of 2 weeks. The radiation dose reached was not reported consistently, recorded doses ranged from a peak single dose of 2.9 Gy [10] to a cumulative dose of 18.46 Gy in one of our cases (Table 1, Guerrero-Putz et al. [present study] case 1).

Alopecia areata (AA) is one of the most important differential diagnoses in this clinical setting. Trichoscopic characteristics are similar between both entities. Wáskiel et al. [11] performed a systematic review in 2018 to update trichoscopic findings in AA, the most frequent trichoscopic features were the following, in order of frequency: yellow dots, black dots, exclamation mark hairs, tapered hairs, broken hairs, short vellus hairs, upright regrowing hairs, and Pohl-Pinkus constrictions. In patients presenting anagen effluvium after neurointerventional radiation, we found that the most frequent features are similar to those found in AA, being yellow dots and black dots the most frequent, followed by short vellus hairs. An important feature of AA that has not been reported in radiation-induced temporary alopecia is exclamation mark hairs, which could be a specific marker for the differential diagnosis.

Histopathology findings have been reported in few cases. Histopathology features include increased numbers of catagen and telogen hairs without perifollicular infiltration, with no peribulbar inflammatory cell infiltrate [3, 10]. Medical history in patients with radiation-induced temporary alopecia often shows that they are undergoing stressful situations and induce doctors to think to “stress induced” AA.

Patients usually do not require treatment, it is important to reassure them that hair regrowth will occur, topical 5% minoxidil BID and intralesional triamcinolone have been utilized [2, 10]. Hair regrowth onset ranges from 2 to 24 weeks after the procedure [5-8, 12-14] up until 12 months after [9].

Hair loss is a known side effect of radiation treatments such as radiotherapy and endovascular procedures. High doses of ionizing radiation, as used for radiotherapy, cause scarring alopecia due to stem cell damage [15]. Low doses as utilized in neurointerventional procedures cause temporary alopecia due to anagen effluvium.

As dermatologists, it is important to think of radiation-induced temporary alopecia in patients who develop patchy hair loss after neurointerventional procedures. Physicians that perform such procedures should be able to anticipate these outcomes among other complications associated with radiation injury and monitor patients throughout the treatment course [16]. Further research including trichoscopic features may help in making the correct diagnosis in a timely manner, avoiding unnecessary treatment as well as to provide a prognosis.

Written informed consent was obtained from the patient for publication of any accompanying images.

The authors have no conflicts of interest to declare.

The authors have no funding sources.

Dr. Guerrero-Putz and Dr. Garza-Rodriguez contributed to the design, drafting of the work, and interpretation of data. Dr. Flores-Dominguez contributed to data analysis and interpretation of data. Dr. Tosti contributed to drafting the work and design. Dr. Castillo-de la Garza contributed to literature and data analysis. Dr. Figueroa-Sanchez contributed to drafting of the work and interpretation of data.