Brodie abscess overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Abdulkerim Yassin, M.B.B.S[2]
Synonyms and keywords: Subacute Osteomyelitis
Overview
Brodie abscess is a rare subacute or acute chronic osteomyelitis with a pus-filled cavity, vascularized wall and hard sclerotic surrounding bone. It mostly involves the metaphysis of bones (especially tibia) but it can occur at any location and in a patients of any age. It classically presents with pain with out any other systemic symptoms. Thus making an accurate and timely diagnosis is usually difficult. It is usually mistaken with bone tumor. It has insidious onset and the inflammatory markers are unremarkable. Brodie abscess may be the result of inadequate treatment for acute osteomyelitis or may occur in the setting of a more strong host resistance to infection, inoculation with less virulent organisms, prior antibiotic exposure or a combination of these factors. Brodie's abscesses are mostly seen in children and adolescents with an average age of 19.5 years. The most commonly identified organism is staphylococcus aureus. Other pathogens such as Pseudomonas aeruginosa, Klebsiella spp., and Salmonella typhi have been reported. In about 25% of cases, no organism is identified. The patient may present with chronic pain in the affected area in the absence of trauma. Laboratory findings are mostly includes normal WBC with differential. Inflammatory markers such Erythrocyte sedimentation rate and C-reactive protein levels are may be normal or elevated in about half of the cases. Definitive diagnosis is made with radiological imaging. The mainstay of treatment is surgical debridementt combined with antibiotics.
Historical Perspectives
Brodie abscess is first described by a British surgeon, sir Benjamin Brodie, in 1832. Wiles reported Brodie abscesses as a specific form of osteomyelitis in 1951. Harris and Kirkaldy-Willis (1965) were the first to describe primary subacute osteomyelitis and present a radiograph diagnosing the condition.
Classification
Brodie abscess was first classified radiologically by Kirkaldy-Willis from East-Africa. The currently utilized classification system was initially proposed by Gledhill in 1973 and then modified by Roberts et al in 1982.
Type IA: Metaphyseal radiolucency without surrounding sclerosis. It may cause confusion with Eosinophilic granuloma. Type IB: Metaphyseal radiolucency with surrounding reactive bone. Type II: Metaphyseal radiolucency with cortical erosion. It resembles Osteosarcoma. Type III: Cortical diaphyseal radiolucency with periosteal reaction. It looks like Osteoid Osteoma. Type IV: Diaphyseal lesion with sub periosteal new bone formation. This type may have the appearance of “onion-skinning” and thus be confused with Ewing’s sarcoma. Type V: Epiphyseal radiolucency that may appear similar to a chondroblastoma. IT has similar appearance with Chondroblastoma. Type VI: Vertebral lesion that may mimic eosinophilic granuloma or tuberculous spondylitis.
Pathophysiology
Local trauma and bacteremia lead to increased susceptibility to bacterial seeding of the metaphysis. history of trauma is reported in 30% of patients. Brodie abscess arises where the bacteria and the host defenses are equally balanced.
Causes
Staphylococcus aureus is the most common pathogens identified, however it is only isolated in as few as 75% of cases.
Differentiating Brodie Abscess From Other Diseases
Other diseases such as osteoid osteoma, Langerhans cell histiocytosis, chondrosarcoma, eosinophilic granuloma or tuberculosis may have similar presentation with brodie abscess and need further investigations.