Brodie abscess is an intraosseous abscess related to a focus of subacute pyogenic osteomyelitis. Unfortunately, there is no reliable way radiographically to exclude a focus of osteomyelitis. It has a protean radiographic appearance and can occur at any location and in a patient of any age. It might or might not be expansile, have a sclerotic or nonsclerotic border, or have associated periostitis.
Typically these present in children with unfused epiphyseal plates, more frequently in boys.
- S. aureus (most common); cultures often negative
It has a predilection for ends (metaphysis) of tubular bones:
- proximal/distal tibial metaphysis (most common)
- carpal and tarsal bones
Rarely traversing the open growth plate; epiphysis (in children and infants).
- lytic lesion often in an oval configuration that is oriented along the long axis of the bone
- surrounded by a thick dense rim of reactive sclerosis that fades imperceptibly into surrounding bone
- lucent tortuous channel extending toward growth plate prior to physeal closure (pathognomonic)
- periosteal new-bone formation +/- adjacent soft-tissue swelling
- may persist for many months
- central intramedullary hypodense cystic lesion with thick rim ossification
- extensive thick well-circumscribed periosteal reaction and bone sclerosis around the lesion could be seen
The “penumbra sign” on magnetic resonance (MR) imaging is useful for discriminating subacute osteomyelitis from other bone lesions. The penumbra sign is a rim lining of an abscess cavity with higher signal intensity than that of the main abscess on T1-weighted images
History and etymology
The lesion is named after Sir Benjamin Collins Brodie (1783-1862), who initially described a chronic inflammatory process affecting the tibia without acute precipitating factors in the 1830's.
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- 3. Afshar A, Mohammadi A. The "Penumbra Sign" on Magnetic Resonance Images of Brodie's Abscess: A Case Report. Iran J Radiol. 2011;8 (4): 245-8. doi:10.5812/iranjradiol.4493 - Free text at pubmed - Pubmed citation