Chronic lung abscess

Chronic lung abscess 

Lung abscess is defined as a circumscribed area of pus or necrotic debris in lung parenchima, which leads to a cavity, and after formation of bronchopulmonary fistula, an air-fluid level inside the cavity.

Lung abscess is in the group of lung infections such as lung gangrene and necrotizing pneumonia which is characterized with multiple abscesses. Lung abscess can be divided on acute (less than 6 weeks) and chronic (more than 6 weeks). 

Chronic Lung abscess

Chronic lung abscess is usually irregular star-like shape with well-defined surrounding to lung parenchyma, fulfilled with grayish line or thick detritus. 

Causes 

Conditions contributing to lung abscess: 

• Aspiration of oropharyngeal or gastric secretion
• Septic emboli
• Necrotizing pneumonia
• Vasculitis: Granulomatosis with polyangiitis
• Necrotizing tumors: 8% to 18% are due to neoplasms across all age groups, higher in older people; primary squamous carcinoma of the lung is the most common.
• Organisms

In the post-antibiotic era pattern of frequency is changing. In older studies anaerobes were found in up to 90% cases but they are much less frequent now.

• Anaerobic bacteria: Actinomyces, Peptostreptococcus, Bacteroides, Fusobacterium, Parvimonas micra species,Microaerophilic streptococcus: Streptococcus milleri
• Aerobic bacteria: Staphylococcus, Klebsiella, Haemophilus, Pseudomonas, Nocardia, Escherichia coli, Streptococcus, Mycobacterium
• Fungi: Candida, Aspergillus, Histoplasma, Blastomyces, and Coccidioides
• Parasites: Entamoeba histolytica, Paragonimus

Symptoms 

Symptoms of a lung abscess commonly come slowly over weeks. They may include:

• Chest pain, especially when you breathe in
• Cough
• Fatigue
• Fever
• Loss of appetite
• Night sweats
• Sputum (a mixture of saliva and mucus) with pus that’s often sour-tasting, foul-smelling, or streaked with blood
• Weight loss

Diagnosis

The following tests are used for the diagnosis of Chronic lung abscess: 

• Chest x-ray
• Often chest CT for better visualization or if endobronchial obstruction is suspected
• Sputum cultures for aerobic bacteria, fungi, and mycobacteria
• Bronchoscopy as needed to exclude cancer, detect unusual pathogens such as fungi or mycobacteria, and in immunocompromised patients
• Culture of any pleural fluid

Depending on the specific findings, rate residuals as interstitial lung disease, restrictive lung disease, or, when obstructive lung disease is the major residual, as chronic bronchitis (DC 6600).