Granuloma annulare subtypes: sonographic features and clinicopathological correlation

Purpose Diagnosis of granuloma annulare (GA) is based on the clinical and histopathological findings. However, only sporadic case reports of subcutaneous GA sonography have been published to date. The objective of this study was to evaluate the ultrasonographic patterns of the different clinical variants of GA: localized, generalized, subcutaneous, and perforating. Methods In this retrospective observational study, we analyzed and correlated the clinical, histopathological, and sonographic features of 15 patients diagnosed with GA. Results We included 8 women and 7 men with a mean age of 48.4 years (8–77 years). We found three different sonographic patterns depending on the clinical variant of GA: poorly defined hypoechoic band including the dermis (dermal pattern), irregularly shaped hypoechoic hypodermal lumps (hypodermal pattern), and ill-defined hypoechoic dermal and subcutaneous lesions (mixed pattern). Five cases showed increased blood flow signal on Doppler interrogation. Conclusion Although our findings are broadly consistent with the previous reports of subcutaneous GA, the sonographic features in localized, generalized, and perforating GA have not been previously reported.