Patterns of Musculoskeletal Involvement in Hidradenitis Suppurativa: A Pilot Study

Background: Despite increasing evidence associating hidradenitis suppurativa (HS) with peripheral arthritis, enthesitis, and axial inflammation, its clinical manifestations and optimal management approaches remain insufficiently studied. Objectives: This pilot study was conducted to characterize patterns of musculoskeletal (MSK) involvement in HS patients, assess disease severity and related metabolic comorbidities, and determine the impact of biologic therapy on symptom control. Methods: A retrospective observational pilot study was conducted involving patients with HS presenting with concurrent MSK symptoms. Clinical data were collected on disease severity, patterns of joint involvement, presence of enthesitis, metabolic parameters, and treatment outcomes. Patients were stratified into axial, peripheral, and mixed MSK phenotypes. Laboratory markers, including glycated hemoglobin (HbA1c), were evaluated to explore potential metabolic associations. Additionally, treatment regimens, comprising nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, and biologic therapies such as tumor necrosis factor (TNF) inhibitors and interleukin-17 (IL-17) inhibitors, were reviewed. Results: Eight patients with HS and concurrent MSK involvement were identified. Among them, 62.5% presented with peripheral arthritis, 12.5% with axial involvement, and 25% with mixed phenotypes. All patients were classified as Hurley stage II or III, with no clear association between disease severity and the pattern of MSK involvement. Enthesitis emerged as a prominent clinical feature, affecting 75% of our patients, most frequently affecting the Achilles tendon and plantar fascia. Metabolic dysfunction was also highly prevalent, including obesity in 62.5% of patients, fatty liver disease in 75%, and elevated HbA1c levels in 75%. NSAIDs provided partial short-term symptomatic relief. In contrast, biologic therapies, particularly IL-17 inhibitor (secukinumab), demonstrated greater efficacy in controlling both MSK and cutaneous manifestations. Notably, patients who were switched from TNF inhibitors to IL-17 inhibitors reported improved clinical outcomes. Conclusions: HS-associated MSK involvement manifests in diverse clinical patterns and is often associated with metabolic comorbidities. Inhibition of IL-17 has emerged as a promising therapeutic approach, particularly for patients who exhibit inadequate responses to TNF inhibitors. However, larger-scale screening and long-term prospective studies are required to better characterize MSK prevalence, onset, clinical patterns, and relationship with cutaneous disease severity and activity, as well as to establish optimal management strategies for HS and HS-associated arthritis.