Sandbox:Aditya
Pathophysiology
The pathogenesis of lung abscess in primary lung abscess is mainly due to aspiration of oral pathogens at the time of altered level of consciousness in conditions such as alcoholism, Seizure disorder.Normally in a healthy individual, the defense mechanisms would cope up with the small amounts of aspirates with no ill effects, however, in conditions like alcoholism, DM, and immunocompromised state these defense mechanisms are compromised leading to decreased activity of alveolar macrophages and mobility of leucocytes.Alcohol also triggers vomiting center which in turn increases the risk of aspiration.
Bronchial obstruction from benign or malignant intrabronchial lesions or extrinsic compression of bronchus as in middle lobe syndrome results in distal abscess formation are causes of secondary lung abscess
It takes around 8-14 days to form a recognizable abscess after aspiration
The Basic pathology of lung abscess is destruction of segment or a portion of lobe, sometimes multiple lobes are involved based on severity of infection ( multiple abscesses ).after the bacterial invasion resulting in the inflammation of the lung tissue and release of various bacterial toxins,along with disrupture of fine blood vessel architecture and release of various proteolytic enzymes from the neutrophils leading to the formation of colliquative necrosis focus
Acute Lung abscess
- Gross morphology: Circumscribed with no so well defined borders with lung parenchyma fulfilled with necrotic debris
- Histopathology: central part of the abscess is filled necrotic tissue mixed with necrotic granulocytes and bacteria
Chronic Lung abscess
- Gross morphology: Irregular in shape with well-defined borders with lung parenchyma filled with grayish and thick detritus
- Histopathology: Abscess with pus with or without bacteria,a layer of pyogenic membrane is present around the abscess through which white blood cells migrate to form the fill the abscess cavitation.Lymphocytes, plasmacells and histiocytes surround the pygogenic membrane in a connective tissue
Location of abscess
- right lung is most commonly involved than the left.
- 75% of the time the abscess presents on the posterior segment of the right apical lobe or apical segments of lower lobes of both the lungs
- lateral part of posterior segment of upper lobe of right lung is most commonly involved in alcoholics
Classification
Based on duration
- Acute : If symptoms are present for less than 6 weeks before presenting to medical care.[1]
- Chronic : If symptoms persist for more than 6 weeks
Based on Etiology
Primary[2] : When Abscess develops among patients who were healthy previously or with high risk factors such as those prone for aspiration
- Aspiration of oropharyngeal secretions
- Immunodeficiency conditions like HIV
- Necrotizing pneumonitis
Secondary : When abscess develops among patients with an underlying lung abnormality
- Bronchial obstruction
- Hematogenic dissemination
- Infection spread from mediastinum
- Coexisting Lung Diseases
Based on mode of spread
Bronchiogenic
- Aspiration of Oropharyngeal secretions
- Bronchial obstruction by Tumor
- Foreign body, Congenital Malformations and Enlarged LymphNodes
Hematogenic
- Infective endocarditis
- Abdominal Sepsis
- Septic Thromboembolism
Risk Factors
Common risk factors in the development of lung abscess are
Common Risk Factors
- Alcoholism
- Seizer disorder
- Artificial ventilation
- Coma
- Neuromuscular disorders with bulbar dysfunction
- Nocturnal Aspiration /Inability to cough
- Bronchial obstruction
- Gingivo-dental sepsis
- Diabetes Mellitus
- Immunosuppression
Less Common Risk factors
- Drug abuse
- Malnutrition
- Mental retardation
- Gastroesophageal reflux disease
Causes
Common causes
- Dental/peridental infections
- Paranasal sinuses
- Alcoholism
- Seuizre disorder
- Patients on artificial ventilation
- patients with tracheoastmy tube
- Intubated patients
- infective endocarditis
- Abdominal sepsis
- IV drug abuse
- Septic thromboembolism
| Cardiovascular | No underlying causes |
| Chemical/Poisoning | No underlying causes |
| Dental | Gingivo-dental sepsis ,Dental/peridental infections |
| Dermatologic | No underlying causes |
| Drug Side Effect | No underlying causes |
| Ear Nose Throat | Paranasal sinusitis |
| Endocrine | Diabetis Mellitus |
| Environmental | No underlying causes |
| Gastroenterologic | GERD,Gastro and esophageal surgeries, |
| Genetic | No underlying causes |
| Hematologic | No underlying causes |
| Iatrogenic | No underlying causes |
| Infectious Disease | Abdominal Sepsis,Infective endocarditis;HIV-AIDS |
| Musculoskeletal/Orthopedic | No underlying causes |
| Neurologic | Seizure disorder,Coma,altered level of consciousness |
| Nutritional/Metabolic | No underlying causes |
| Obstetric/Gynecologic | No underlying causes |
| Oncologic | No underlying causes |
| Ophthalmologic | No underlying causes |
| Overdose/Toxicity | No underlying causes |
| Psychiatric | No underlying causes |
| Pulmonary | Bronchiectasis;Cystic fibrosis;Bullous emphysema;Bronchial obstruction by tumor, foreign body or
enlarged lymph nodes;Congenital malformations (pulmonary sequestration, vasculitis, cystitis);Infected pulmonary infarcts;Pulmonary contusion;Broncho-oesophageal fistula. |
| Renal/Electrolyte | No underlying causes |
| Rheumatology/Immunology/Allergy | Immunosuppresents ,corticosteroid therapy |
| Sexual | No underlying causes |
| Trauma | No underlying causes |
| Urologic | No underlying causes |
| Miscellaneous | No underlying causes |
- ↑ Puligandla PS, Laberge JM (2008). "Respiratory infections: pneumonia, lung abscess, and empyema". Semin. Pediatr. Surg. 17 (1): 42–52. doi:10.1053/j.sempedsurg.2007.10.007. PMID 18158141.
- ↑ Wali SO (2012). "An update on the drainage of pyogenic lung abscesses". Ann Thorac Med. 7 (1): 3–7. doi:10.4103/1817-1737.91552. PMC 3277038. PMID 22347342.