“Dot-in-circle sign:” An ultrasound and magnetic resonance imaging sign for mycetoma

Abstract

Mycetomas are chronic infections of the skin, underlying soft tissues, and sometimes extending up to the bones. They can be actinomycetoma or eumycetoma. Mycetoma is more frequent in tropical and subtropical regions. The definitive diagnosis is made by histopathology and culture in most cases, but these procedures are invasive and time consuming. “Dot-in-circle sign” is an important sign present on both ultrasound (USG) and magnetic resonance imaging (MRI) which imply the presence of distinct hypoechoic lesions surrounding a hyperechoic center. The use of these imaging modalities can help in the early diagnosis and preventing complications. We report two cases of eumycetoma affecting the feet, with characteristic USG and MRI features.