Patients with bullous pemphigoid and comorbid psoriasis present with less blisters and lower serum levels of anti-BP180 autoantibodies.

BACKGROUND

Although the association of bullous pemphigoid (BP) and psoriasis is well-established, the clinical and immunological features of patients with coexisting BP and psoriasis are yet to be investigated.

OBJECTIVE

We aimed to estimate the prevalence of psoriasis amongst patients with BP and to elucidate the clinical and immunological characteristics of BP patients with comorbid psoriasis.

METHODS

A retrospective cohort study including all consecutive patients diagnosed with BP throughout the years 2009-2019 in a tertiary referral centre.

RESULTS

The study encompassed 273 patients with BP, of whom 11 (4.0%; 95% CI, 2.3-7.1%) had comorbid psoriasis. The onset of psoriasis preceded that of BP in 81.8% of patients by a median (range) latency of 26.5 (5.0-34.0) years. Compared to BP patients without psoriasis, those with BP and comorbid psoriasis were significantly younger at the onset of BP [71.8 (9.3) vs. 79.4 (9.8) years; P = 0.023], had a milder erosive phenotype [erosion/blister BPDAI mean (SD)score; 5 (4.1) vs. 22.3 (15.2); P = 0.025], lower levels of anti-BP180 NC16A serum autoantibodies [236.6 (266.3) vs. 556.2 (1323.6) U/mL; P = 0.008] and a higher prevalence of isolated linear C3 deposits (36.4% vs. 14.1%; P = 0.043) and a lower prevalence of linear immunoglobulin G deposits (36.4% vs. 68.7%; P = 0.025) along the dermal-epidermal junction by direct immunofluorescence microscopy.

CONCLUSIONS

Patients with BP and comorbid psoriasis present at a younger age with milder erosive phenotype and lower levels of pathogenic autoantibodies.