The dot-in-circle sign of mycetoma on MRI

Mycetoma is a chronic granulomatous disease prevalent in tropical countries, but it also occurs in Europe and the United States. Early diagnosis is important as it has therapeutic implications. Although biopsy and microbiological culture provide the definitive diagnosis, these are difficult to achieve in many instances. The dot-in-circle sign is a recently proposed magnetic resonance imaging (MRI) sign of mycetoma, which is likely to be highly specific. We present a case of mycetoma of the thigh with characteristic MRI features. To the best of our knowledge, only 2 cases of mycetoma of the foot demonstrating this sign have been previously published.