Chest wall infection refers to infectious lesions occurring in the various structures and tissues of the chest wall, including the skin, subcutaneous tissues, ribs, muscles, and other internal structures of the chest wall. The infection is typically caused by bacteria or other pathogens, and can affect any part of the chest wall.

Chest wall infection can occur for various reasons, with the six most common including:

1. Trauma: Traumatic injuries such as severe impacts, stab wounds, or surgeries can damage chest wall tissues, creating an opportunity for bacteria or other pathogens to invade and trigger an infection.

2. Thoracic surgery (such as cardiac surgery, lung surgery, etc.) or other diagnostic and therapeutic procedures (like chest tube insertion or chest tube drainage) can compromise the integrity of the chest wall and increase the risk of infection. Additionally, if aseptic techniques are not strictly followed during the procedure, or if there are issues with the sterilization of instruments, materials, or dressings, postoperative infections can occur.

3. Cryptic infection: Cryptic infection, which can also be regarded as a primary infection, presents with insidious onset and unknown etiology. The most probable cause is the hematogenous spread of infections from other body sites, such as in the case of tuberculous chest wall infection.

4. Direct spread: If the infectious foci in the lungs or thoracic cavity isn’t promptly managed, the infection may spread to the chest wall, leading to chest wall infection.

5. Localized necrosis of chest wall tissue: Necrosis in localized areas of the chest wall can lead to skin breakdown, creating openings for bacteria to enter and cause chest wall infection.

6. Weakened immune system: Patients with certain immunodeficiency disorders (such as AIDS), chronic diseases (such as diabetes, hepatic or renal insufficiency), or those receiving treatments that suppress the immune system (such as chemotherapy) are more prone to infection due to their reduced resistance.

In addition to localized pain, other possible symptoms include fever, headache, muscle soreness, and fatigue, etc.

The methods for diagnosing chest wall infections can vary depending on the specific circumstances. Here are some common diagnostic approaches:

1. Physical examination: A thorough inspection of the patient's chest is conducted to check for symptoms such as redness, swelling, and ulcers. Palpation for pain is also performed to assess the severity and extent of the infection.

2. Blood test: Blood samples are taken to assess the infection, including measurements of white blood cell count and inflammatory markers.

3. Imaging test: This include X-ray, CT scan, MRI, 3D reconstruction, and ultrasound, etc.. These tests help determine the location, extent, and severity of the infection.

4. Bacterial culture: Samples (such as pus or secretions) are taken from the infected site for bacterial culture and susceptibility testing. This helps identify the pathogens that cause the infection and determine the appropriate antibiotic treatment.

5. Biopsy: By obtaining a sample of chest wall tissue, further analysis of pathological and bacteriological characteristics is conducted.

Treatment for chest wall infection is divided into two approaches: conservative treatment and surgical intervention.

1. Conservative treatment: For milder infection, conservative treatment can be considered. These typically include antibiotic therapy, nutritional support, and local dressing changes.

2. Surgical intervention: For severe chest wall infection, surgical intervention is necessary to remove infectious foci and drain purulent fluid. These include incising and draining abscesses, debriding necrotic tissue, or repairing damaged chest wall structure (such as filling in soft tissue defects or reconstructing missing bone structure with autologous bone).