Pediatric Subacute Osteomyelitis

  • Etiology:
    — Is intraosseous abscess
    — Staphylococcus aureus most common
    — Subacute osteomyelitis can persist for years before converting to frank osteomyelitis and resulting in a Brodie abscess
  • Imaging Radiograph:
    — Radiolucent center with reactive sclerosis and surrounding granulation tissue
    — Lucent channel extending to physis is pathognomonic
    — Sclerotic rim on radiograph fades away
  • Imaging MRI:
    — Penumbra sign – central abscess fluid
    — Enhancing high signal granulation tissue (penumbra)
    — Very low signal sclerotic rim of bone sclerosis (dark on all MRI sequences)
    — Low signal peri-lesional marrow edema
  • DDX:
  • Complications:
  • Treatment: Antibiotics
  • Clinical:
    — May be afebrile with normal inflammatory marker levels
    — May present with draining abscess

Radiology Cases of Subacute Osteomyelitis with Brodie Abscess

MRI of subacute osteomyelitis / Brodie abscess
Sagittal T1 MRI without contrast of the knee (left) shows a small round low signal intensity lesion in the middle of the proximal tibia that is surrounded by low signal intensity peri-lesional marrow edema. Sagittal T1 MRI with contrast (center) better demonstrates the small round low signal intensity lesion and coronal T1 MRI with contrast (right) shows a faint enhancing ring (penumbra) around the lesion.