Real-Time, Noninvasive Diagnosis of Bullous Pemphigoid: Diagnostic Performance of Line-Field Confocal Optical Coherence Tomography.

Background: Bullous pemphigoid (BP) is a common autoimmune blistering dermatosis often difficult to distinguish from other inflammatory conditions. Timely diagnosis is crucial for appropriate management. Line-field confocal optical coherence tomography (LC-OCT), a noninvasive imaging technique that uses an 800nm laser to generate high-resolution vertical and horizontal cross-sectional images of the skin, is evaluated as a diagnostic tool for BP.

Materials and methods: A prospective, single-center study was conducted on 26 patients with suspected BP. LC-OCT imaging, histopathology, and direct immunofluorescence (DIF) were performed. LC-OCT images were assessed for the presence of key diagnostic features, including subepidermal cleavage and eczema criteria.

Results: Based on histopathology, DIF, indirect immunofluorescence (IIF), and ELISA, the final diagnoses were 15 BP cases and 11 non-BP cases. LC-OCT correctly identified 12 of 15 BP cases and all 11 non-BP cases, demonstrating a sensitivity of 0.8 and a specificity of 1.0. The presence of subepidermal cleavage was a key diagnostic criterion for BP (p = 0.000). The absence of alternating hypo- and hyper-reflective layers (p = 0.000), thickened and disrupted stratum corneum (p = 0.014), spongiosis (p = 0.036), and thickened epidermis (p = 0.043), which occurred significantly less frequently in BP cases, further supported the diagnosis.

Conclusion: LC-OCT demonstrates high sensitivity and specificity in diagnosing BP, offering a rapid, point-of-care diagnostic approach. LC-OCT can be used to evaluate unclear inflammatory skin conditions and guide further investigations. However, LC-OCT has limitations in diagnosing non-bullous stages of BP; thus, histology and DIF remain the gold standard for definitive diagnosis.