Pain and inflammation in hidradenitis suppurativa correspond to morphological changes identified by high-frequency ultrasound

Background Hidradenitis suppurativa (HS) is an inflammatory skin disease with a chronic intermittent course. The current classification systems used to categorize disease severity provide limited insight into the degree of inflammation and pain, which are key symptoms of the disease. Objective We sought to investigate the correlation and validity of simple patient- and investigator-assessed items related to inflammation with morphological changes identified by high-frequency ultrasound in HS. Methods Twenty patients with the clinical diagnosis of HS were enrolled in this study. All patients underwent clinical examinations during which one representative inflammatory nodule was selected in each patient based on the anamnestic information, patient experience and clinical presentation. Tenderness and flare activity of the representative nodule were graded by the patients and erythema by the investigator. Subsequently, all patients underwent high-resolution ultrasound scanning of their representative nodule. Results We found significant associations between the size of the representative nodule (the diameter in the transverse plane) and patient assessments of flare activity and tenderness. Moreover, we found a marked association between the size of the nodules and investigator assessment of erythema. Conclusion Patient assessments of flare activity and pain, and investigator assessment of erythema are strongly associated with morphological changes identified using ultrasound, suggesting that these patient- and investigator-assessed items might be strong indicators of the degree of present inflammation in HS