Abstract: 【Abstract】 Objective To investigate the optical coherence tomography （OCT）imaging features of bullous pemphigoid （BP） and pemphigus. Methods A total of 23 patients with BP and 18 with pemphigus diagnosed according to clinical manifestations, histopathological and immunological features were collected from Wuhan No.1 Hospital from January to June 2024. OCT imaging was performed in 41 patients to observe the blisters at the lesion sites and their anatomic locations （intraepidermal or subepidermal）, intravesicular inflammatory cells and fibrin deposits, dilated vessels in the upper dermis, as well as skin adjacent to the lesions. Results Among the 23 patients with BP and 18 patients with pemphigus （including 12 with pemphigus vulgaris and 6 with pemphigus foliaceus）, there were 20 males and 21 females, and their ages at onset ranged from 20 to 89 years. OCT imaging of blisters in patients with BP showed subepidermal oval to round hyporeflective liquid-filled areas containing highly refractive inflammatory cells and fibrin deposits, with dilated vessels in the upper dermis, while OCT imaging of blisters in patients with pemphigus showed intraepidermal blisters with a few inflammatory cells; the OCT imaging features of both BP and pemphigus were similar to their corresponding histopathological features. The detection rates of intravesicular inflammatory cells and fibrin deposition were significantly higher in the patients with BP （82.61% ［19/23］, 60.87% ［14/23］, respectively） than in those with pemphigus （44.44% ［8/18］, 11.11% ［2/18］; χ2 = 6.54, 10.51, P = 0.011, 0.001, respectively）. In the OCT images of normal skin adjacent to blisters, subclinical fissures were detected in 17.39% （8/46） of patients with BP and 25.00% （9/36） of patients with pemphigus. Conclusion OCT imaging could accurately locate the blisters and potential subclinical lesions in normal skin adjacent to blisters in patients with BP and pemphigus, which is helpful for the early auxiliary diagnosis of these two diseases.

Key words: Pemphigoid, bullous, Pemphigus, Optical coherence tomography, Diagnosis