Sonographic Characteristics of Fistulous Lesions in Facial Acne: A Comprehensive Analysis

This study aimed to investigate the sonographic characteristics of fistulous lesions in facial acne.

Facial acne patients were classified based on clinical grading criteria, with or without fistulous lesions, and subsequently underwent high-frequency ultrasound assessment to evaluate lesion characteristics. Statistical analyses were conducted to compare clinical and sonographic features between fistula and nonfistula groups.

A total of 2355 acne lesions in 189 patients were studied, and 343 fistulous lesions were detected in 71 patients (fistula group). The male proportion and the age of the fistula group were higher than those of the nonfistula group (50.70% vs. 30.51%; 23.21 vs. 26.72, respectively). Among the fistula group, a strong positive correlation was found between the highest grade of fistulous lesions per patient and the highest grade of each patient (r_s = 0.853, p < 0.001). In the fistula group (totaling 909 lesions), the length of fistulous lesions was significantly greater than that of nonfistulous lesions (F = 251.339, p < 0.001). Across all 189 patients, dermal thickness, lesion depth, lesion length, and lesion area were significantly greater in the fistula group compared to the nonfistula group (dermal thickness: t = 19.582, p < 0.001; depth: t = 7.613, p < 0.001; length: t = 21.169, p < 0.001; lesion area: z = -20.580, p < 0.001, respectively). High-frequency ultrasound revealed thickened dermal layers in acne lesions, with fistulas present across various skin layers, including the epidermis, dermis, and subcutaneous tissue. Fistulous lesions typically presented as low banded pattern echoes (length-to-depth ratio ≥ 3:1), with blood flow signals varying according to inflammatory activity.

High-frequency ultrasound effectively characterizes fistulous lesions in facial acne, providing critical insights for clinical management and further clinical research.