Ultrasound in-depth characterization and staging of hidradenitis suppurativa.

Background: The clinical diagnosis of fistulous tracts and recurrent fluid collections in hidradenitis suppurativa (HS) may be complex. Information on subclinical involvement and grading of severity may improve management.

Objective: To study HS lesions and evaluate the relevance of adding ultrasound (US) to the clinical examination.

Methods And Materials: We reviewed the sonograms of consecutive patients with HS from January 1, 2010 to May 31, 2012. The abnormalities observed in the US examinations were organized, classified, and integrated into a clinical-sonographic scoring system (SOS-HS), to stage the disease.

Results: Thirty-four patients with HS with a total of 142 lesional areas were evaluated. US findings included subclinical fluid collections in 76.4% of the patients, fistulous tracts in 29.4%, dermal pseudocysts in 70.6%, and widening of the hair follicles in 100%. Concordance with the clinical HS scoring performed by dermatologists showed a significant fair agreement (k = 0.30; p < .001); concordance of SOS-HS with clinical scores was acceptable but significantly lower (k = 0.27; p = .02) because clinical scores consistently underestimated disease stage and severity.

Conclusion: US examination of HS lesions provides anatomic information that is clinically unavailable. HS is possible to stage sonographically.