Target sign

A dermatological or radiologic pattern characterized by concentric rings or a central nodular opacity within a surrounding ring-like opacity. Observed in various settings such as skin (erythema migrans, erythema multiforme, medication reaction, fixed drug eruptions), GI disease (intussusception, Crohn's disease, bowel infection/ischemia, GI cancer), schwannoma, CNS tuberculoma, and liver metastasis.