Suitability of high‐frequency ultrasonography (20 MHz) in evaluation of various forms of primary cicatricial alopecia in relation to trichoscopy — pilot study

Abstract Background Primary cicatricial alopecia is a potentially irreversible process of hair loss, in which for proper diagnosis a skin biopsy is necessary. Searching for new, non‐invasive diagnostic methods may shorten the time for final diagnosis, initiating appropriate treatment and reduce the need for biopsy. The aim of this study was to evaluate the usefulness of high‐frequency ultrasonography (HF‐USG) as a diagnostic method in patients with primary scarring alopecia and to compare it with trichoscopy. Materials and methods The study covered a total of 44 adults: 8 with classic lichen planopilaris (LPP), 11 with discoid lupus erythematosus (DLE), 14 with frontal fibrosing alopecia (FFA), and 11 healthy volunteers. Each patient underwent physical and trichoscopic examination which was the base for qualification for active/inactive stage of the disease. Then, HF‐USG was performed using a probe with a frequency of 20 MHz. In HF‐USG images, the following elements were evaluated and measured: entrance echo (EE), follicular structures (FS), dermal background (DB), and dermal/subdermal border (D/SB). Results Inactive phase was characterized by significantly lower number/lack of FS compared to the active phase of scarring alopecia. HF‐USG of active LPP/FFA presented cigar‐like shaped FS, while inactive stage pronounced D/SB forming saw‐like pattern. Active DLE in HF‐USG were associated with focal, doubled EE and widened FS with a tendency to create hypoechogenic wide, structureless bands within the skin. In inactive DLE, there was no specific pattern of D/SB or rarely puzzle‐like pattern. Conclusion HF‐USG images differ depending on the phase of the disease and the type of scarring alopecia, similarly to trichoscopic examination.