Immunological features and factors associated with mucocutaneous bullous pemphigoid – a retrospective cohort study

Background and objectives: The features of bullous pemphigoid (BP) patients presenting with mucosal lesions are not established. We aimed to elucidate the clinical and immunological features of BP patients with mucosal involvement, and to identify factors associated with mucosal lesions. Patients and methods: A retrospective study encompassing all consecutive patients diagnosed with BP throughout the years 2009–2019 in a tertiary referral center. Results: The study encompassed 273 patients with BP, of whom 31 (11.4 %) presented with mucosal lesions. The oral mucosa was the most frequently affected mucosal surface (71.0 %), followed by the genital (25.8 %) and the nasal (22.6 %) mucosae. Relative to other patients with BP, patients with mucosal involvement had a more prominent palmoplantar involvement (67.7 % vs. 37.2 %; P = 0.001); lower seropositivity rate (18.2 % vs. 54.2 %; P = 0.027) and lower levels (29.3 ± 64.5 vs. 129.5 ± 304.4 U/ml; P = 0.016) of anti-BP230 autoantibodies; and decreased peripheral eosinophil counts (760.0 ± 638.6 vs. 1296.3 ± 1013.7; P < 0.001). Absence of anti-BP230 autoantibodies (OR, 5.32; 95 % CI, 1.07–26.32; P = 0.026) and lack of peripheral eosinophilia (OR, 4.31; 95 % CI, 1.14–16.39; P = 0.021) were associated with the presence of mucosal involvement in BP. Conclusions: Mucosal involvement is present in a notable subgroup of patients with BP and is associated with the absence of both anti-BP230 antibodies and peripheral eosinophilia.