Amyloidosis in hidradenitis suppurativa: a cross-sectional study and review of the literature

Background: Coexistence of hidradenitis suppurativa (HS) and amyloidosis has been anecdotally described, but the association between these conditions is yet to be firmly established. Aim: To study the association between HS and amyloidosis using a large-scale computerized database, and to perform a literature review to characterize all reported patients with coexistent HS and amyloidosis. Methods: A cross-sectional study was conducted comparing the prevalence of amyloidosis among patients with HS and age-, sex- and ethnicity-matched healthy controls (HCs). Additionally, a review of literature was performed to summarize all reported cases with a dual diagnosis of both conditions. Results: In total, 4417 patients with HS and 22 085 controls were included in the study. The prevalence of amyloidosis was increased in patients with HS compared with the HC group [n = 7 (0.2%) vs. n = 2 (0.0%), respectively; OR = 17.5; 95% CI 3.6–84.4; P < 0.001]. In a multivariate analysis, HS was still associated with amyloidosis (OR = 11.2; 95% CI 1.3–94.5; P = 0.03). The literature review identified nine patients who developed amyloidosis during the course of HS, with 44.4% eventually having renal failure. ‬Favourable outcomes were reported in patients managed by tumour necrosis factor (TNF)-α inhibitors. Conclusion: This study establishes the association between HS and amyloidosis. Screening for amyloidosis may be considered in patients with HS with a relevant clinical picture, mainly proteinuria. TNF-α inhibitors may be preferred in patients with a dual diagnosis of these conditions.