Brodie abscess overview
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.

# 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.

# Epidemiology and Demographics
Brodie's abscesses is generally observed in patients younger than 25 years of age, mostly seen in children and adolescents with an average age of 19.5 years.

# Risk Factors
The development of brodie`s abscess could be the result of many factors such as inadequate treatment of acute osteomyelitis or antibiotic resistance.

# Natural History, Complications and Prognosis
Brodie`s abscess is a rare subacute osteomyelitis. It is usually located within the metaphysis of long bones although diaphyseal involvement is more common in adult. Tibia is the most commonly involved bone. If left untreated,, it may cause long term disability, fracture or amputation. Prognosis is excellent after effective treatment.

# Diagnosis

## History and Symptoms
Brodie's abscesses are mostly seen in children and adolescents. It has gradual onset and can be difficult to diagnose. It presents mainly with bone pain.

## Physical Examinations
The main presenting physical signs are limping, swelling and erythema.

## Laboratory Findings
Laboratory findings such as white blood cell count and differential usually shows normal. Erythrocyte sedimentation rate and C-reactive protein levels may be normal or could be elevated.

## X-ray
The diagnosis is made mainly with radiological imaging.

## CT Scan
CT-Scan reveals the same features as x-ray but additionally It enhances sinus tract and fistula to a joint or soft tissue.

## MRI
Definitive diagnosis is made using MRI.

## Other Imaging Findings
SPECT-CT is also used to diagnose brodie`s abscess.

## Other Diagnostic Studies
Blood culture and histological examination of the surgical specimen help to diagnose brodie`s abscess.

# Treatment

## Medical Therapy
The combination of surgical debridement with antibiotics are the mainstay of treatment.

## Surgical Therapy
Surgical debridement includes removal of all necrotic, dead bones and infected granulation tissues.

## Primary Prevention
No data available for the primary prevention of brodie abscess.

## Secondary Prevention
No data available for the secondary prevention of brodie abscess.