The role of trichoscopy in the differential diagnosis of frontal alopecia of the scalp

Alopecia or hair loss is a common condition that often causes psychological stress in patients. Clinical and physical examination findings are not always sufficient for the differential diagnosis of alopecia. Due to being an invasive procedure, scalp biopsy is not always performed. Trichoscopy (hair and scalp dermatoscopy) is used for diagnosing and following-up hair diseases, also a rapid and non-invasive technique allowing us to recognize invisible morphological structures with the naked eye. Trichoscopy needs to be standardized to improve its accuracy and consistency. It is aimed to make differential diagnoses of diseases like traction alopecia (TA), male pattern hair loss (MAGA), female pattern hair loss (FAGA) and telogen effluvium (TE) affecting also frontal scalp with trichoscopy and to contribute to trichoscopic standardization. Between December 2023 and May 2024, 107 patients with alopecia including the frontal region, 30 of whom were diagnosed as FAGA, 17 as MAGA, 28 as TA, 25 as TE, 3 as frontal fibrosing alopecia and 4 as trichotillomania were included in the study. Demographic and clinical characteristics, skin phototypes, turban use, hair tying style and hair styling method were recorded. The frontal, vertex, temporal and occipital regions of the scalp were photographed using a videodermoscope and each region was evaluated trichoscopically with 4 images under 6 main categories: hair shaft findings, follicular findings, perifollicular findings, hair distribution pattern, vascular pattern and scalp findings. Data were analyzed using SPSS (Statistical Package for the Social Sciences) version 29.0. Regrowing hairs sign in the frontal region was observed in 23 (92%) patients with TE, 19 (67.9%) patients with TA, 10 (33.3%) patients with FAGA and 4 (23.5%) patients with MAGA. Hair powder in the frontal region was observed in 5 (17.9%) patients diagnosed with TA and 1 (5.9%) patient diagnosed with MAGA, but not in any patient diagnosed with TE and FAGA. Hair diameter diversity in the frontal region was observed in 27 (90%) patients with FAGA, 17 (100%) patients with MAGA, 25 (89.3%) patients with TA and 9 (36%) patients with TE. Peripilar sign in the vertex was observed in 2 patients (6.7%) with FAGA, 4 patients (23.5%) with MAGA and 1 patient (3.6%) with TA. Peripilar sign was not observed in any patient diagnosed with TE. The mean number of single hair follicular unit findings in the frontal region was significantly higher in FAGA (10.70 ± 6.59), MAGA (13.12 ± 9.05) and TA (9.21 ± 3.99) than in TE (4.16 ± 2.88) groups in patients. The mean number of vellus hair findings in the frontal region was significantly higher in MAGA (16.18 ± 13.12) than in FAGA (4.63 ± 5.92) and TE (1.16 ± 2.49) groups in the patients. The mean number of vellüs hair findings in the frontal region was significantly higher in FAGA and TA (6.11 ± 4.55) than in TE groups in the patients. The mean number of thin hair findings in the frontal region was significantly higher in FAGA (14.30 ± 7.55), MAGA (16.35 ± 8.35) and TA (12.07 ± 5.08) than in TE (5.84 ± 4.42) groups in the patients. Our results suggest that trichoscopy is useful in the differential diagnosis of alopecia and may reduce the need for scalp biopsy. Our study may pioneer innovations regarding more efficient and accurate use of trichoscopy in alopecias with difficult differential diagnosis. Further studies are needed to standardize trichoscopic findings and trichoscopy using in alopecias.