Abstract
This report presents the “penumbra sign” of Brodie’s abscess in a 17-year-old boy. The lesion was located in the proximal metaphysis of the left tibia. Histologic and microbiologic confirmation of the diagnosis was made. A “penumbra sign” on non-contrast enhanced T1-weighted magnetic resonance images is a helpful diagnostic sign of Brodie’s abscess.
Highlights
Brodie’s abscess is a primary subacute osteomyelitis that is characterized by localized intraosseous collection of abscess [1,2]
It is seen on plain radiograph as a radiolucent lesion with a well-defined marginal sclerosis, most often in the proximal metaphysis of tibia, usually in a young patient prior to epiphyseal closure [2,3]
This report highlights the importance of a ‘penumbra sign’ in differentiating between Brodie’s abscess and other bone tumors or lesions on magnetic resonance (MR) imaging
Summary
Brodie’s abscess is a primary subacute osteomyelitis that is characterized by localized intraosseous collection of abscess [1,2] It is seen on plain radiograph as a radiolucent lesion with a well-defined marginal sclerosis, most often in the proximal metaphysis of tibia, usually in a young patient prior to epiphyseal closure [2,3]. Plain radiographs of the left knee showed an irregular radiolucent lesion with no significant marginal sclerosis in the proximal metaphysis of tibia [Figure 1]. MR imaging revealed an irregular hypointense intramedullary lesion in the proximal metaphysis of tibia on non-contrast enhanced T1-weighted images with a surrounding rim of high signal intensity (‘penumbra sign’) [Figure 2].
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