Preliminary Application of High-Frequency Ultrasound in the Differentiation of Pemphigus and Bullous Pemphigoid: An Observational Study

Abstract

Objective: Ultrasonography is a diagnostic imaging technique used to visualize subcutaneous body structures for identification of possible pathologies. In this study, we aimed to explore the clinical significance of high-frequency ultrasound in differentiating the location of blisters between pemphigus and bullous pemphigoid. Methods: Eighteen patients were recruited in Department of Dermatology, Zhongda Hospital from 2020 to 2021 and divided into a pemphigus group (n = 8) and a bullous pemphigoid group (n = 10) according to the diagnostic criteria for each. Ultrasonographic images were collected using a 50-MHz high-frequency ultrasound system. The indexes of ultrasonic evaluation were the layer (epidermis or dermis), size, shape, internal echo, and boundary of the blister. Categorical variables are expressed as n (%), and differences were compared using Fisher’s exact test. Results: The ultrasonographic images in the pemphigus group showed an intraepidermal semi-arc or irregular anechoic or hypoechoic areas. The inferior borders were situated above the characteristic thin linear hyperechoic bands of the epidermis. A linear hypoechoic band was present at the dermoepidermal junction in some cases. In the ultrasonographic images of the bullous pemphigoid group, the linear hyperechoic bands of the epidermis were continuous and intact. An oval fluid anechoic area (subepidermal blister) was present immediately below the bands. The location of the blisters in the ultrasonographic images was significantly different between the 2 groups (P < 0.001). Conclusion: High-frequency ultrasound can be used as an auxiliary means to differentiate the location of blisters between pemphigus and bullous pemphigoid.