Prevalence of clinical and ultrasound enthesitis in patients with hidradenitis suppurativa

Hidradenitis Suppurativa (HS), also called acne inversa, is a chronic
inflammatory disease of the skin. HS is associated with metabolic changes like
dyslipidaemia and other chronic inflammatory diseases like inflammatory bowel
disease (IBD), acne conglobata and spondyloarthritis These conditions share a
dysregulation of the innate immune system, which is supported by the fact that
the HS lesions are characterised by an enhanced expression of neutrophils and
macrophages. Recent studies have shown that there is a high association of HS
with inflammatory back pain. There was also found a high prevalence of patients
with enthesitis. Enthesitis is a central feature of spondyloarthritis (SpA).
The presence of a peripheral enthesitis is used in the European
Spondylarthropathy Study Group Criteria for SpA. It is hard to detect a SpA
early, because of the poor specificity of symptoms of SpA. Diagnostic
investigation of a possible enthesitis with ultrasound is a highly useful and
sensitive tool in the evaluation of enthesitis and improves the ability of
clinical examination. Evidence of common inflammatory pathways and the fact
that the prevalence of inflammatory rheumatology disorders is higher in
patients with HS provides adequate support for future studies to continue
investigating the relationship between SpA en HS. The aim of this study is to
investigate the prevalence of a clinical enthesitis in patients with HS using
clinical examination and ultrasonography as golden standard.

To determine the prevalence of enthesitis, both clinical and on US, in patients
with HS.

A mono-centre, descriptive, cross-sectional study.

The participants data will be collected during physical examination and an
ultrasound. Dermographic data will be collected from the chart. These
examinations are minimal invasive with a neglectable risk. The burden of the
patient is restricted to one visit of the outpatient clinic with the duration
of one hour.