ULTRASOUND EXAMINATION OF HAIR-FOLLICLES IN HIDRADENITIS SUPPURATIVA

Objective: To describe the in vivo skin echostructure, hair follicle s hape, and dermal thickness in hidradenitis suppurativa. Design: Qualit ative and quantitative assessment of high-frequency (20-MHz) B-mode ul trasound images of lesional and paralesional skin. Setting: University hospital. Patients: Age-and sex-matched outpatients with hidradenitis suppurativa (n=15) and healthy control subjects (n=13). Median age wa s 34 years (range, 31-38). Results: Clinically normal paralesional hai r follicles in hidradenitis have an abnormal shape. The follicles appe ar to be wider in the deep dermis, the difference being statistically significant in the genitofemoral region (P=.007). Patients with hidrad enitis have larger follicles in the axilla than controls (P=.002). Mat ure acne and hidradenitis lesions are indistinguishable, but both are different from epidermal cysts. Mean axillary and genitofemoral skin w as significantly thicker in patients than in controls. Conclusions: In vivo ultrasonography shows characteristic differences in the shape of hair follicles in hidradenitis. The general underlying abnormalities appear to occur in the deep part of the follicle. The mature lesions a re indistinguishable from acne, but are clearly different from epiderm al cysts. A thickened skin may play a pathogenic role in the developme nt of hidradenitis.