Use of trichoscopy for the diagnosis of alopecia areata coexisting with primary scarring alopecia in a female hair loss patient.

Despite patchy hair loss being typically observed in alopecia areata (AA), similar lesions can be seen in other forms of alopecia and the diagnosis is sometimes challenging. Of note, patchy primary scarring alopecia (SA) needs to be clearly distinguished from AA as SA can leave permanent hair loss. Herein, we report a previously unreported case of AA coexisting with SA successfully diagnosed by detailed trichoscopic investigation. A 42-year-old woman visited us with patchy hair loss lesions on the scalp. On physical examination, alopecic lesions sized up to 2 cm in diameter were observed in the right temporal and parietal regions. A gentle hair pull test collected dystrophic anagen hairs from some patches. Trichoscopy detected tapering hairs and black dots. The diagnosis of AA was made. However, some reddish patches were totally hair pull test negative, urging us to further evaluate the remaining lesions. Additional trichoscopic investigation revealed the disappearance of follicular ostia and the presence of a white and milky-red area and peripilar scales, suggestive of SA. In histology, the clinically AA lesion showed peribulbar cell infiltration, while the potentially SA lesion demonstrated inflammatory cell infiltration around the isthmus and the decrease in hair follicles, some of which were replaced by fibrotic tissue. The final diagnosis of AA coexisting with SA was made. Intralesional corticosteroid injection improved AA but not SA. These findings emphasize the need for thorough trichoscopic examination for accurate diagnoses of rare hair loss conditions.