Frontal Fibrosing Alopecia: A Histopathological Comparison of the Frontal Hairline with Normal-Appearing Scalp

Frontal fibrosing alopecia is characterized by the presence of a lymphocytic inflammatory infiltrate around the upper follicle and by perifollicular fibrosis, which results in the destruction of the hair follicle. Recent reports have also found the presence of those findings in clinically unaffected areas. The aim of this report is to perform a deeper analysis of the histopathological features of this apparently unaffected scalp. A cross-sectional study including 52 women with frontal fibrosing alopecia was performed. Two areas were biopsied: the frontal hairline and a normal-appearing scalp area. Sebaceous glands were reduced/absent in 80.8% of the frontal hairline samples compared to 42.3% of the "healthy scalp" samples (p = 0.001). Inflammatory infiltrate was observed in 92.3% of patients in the frontal hairline and in 86.5% of them in the "healthy scalp" area (p = 0.508), although the severity was higher in the former (p = 0.013). Follicular epithelium changes were seen in 70.6% of the frontal hairline biopsies compared to 48.1% of the "healthy scalp" biopsies (p = 0.012). Fibrous tissular changes were noted in 80.8% and 53.8% of the frontal hairline and "healthy scalp" biopsies, respectively (p = 0.003). In conclusion, the histopathological features of frontal fibrosing alopecia are shared by both affected and clinically unaffected areas.