A lung abscess is a cavity in the lung that contains pus and is surrounded by a pyogenic membrane formed from granulation tissue and a layer of fibrous fibers.
Pulmonary gangrene is a very serious pathological condition characterized by massive necrosis and putrefaction, rapid purulent fusion and rejection of lung tissue without a clear restriction from the healthy part.
There is also a gangrenous abscess, which has a smaller area and is delimited (unlike common gangrene). This is the process of necrosis of the lung tissue, during the demarcation of which a cavity is formed with parietal or free-lying sequesters of the lung tissue and a tendency to gradual purification.
The concept of “destructive pneumonitis” includes the three above-defined diseases. Most often, a lung abscess is fixed in men who are from 20 to 50 years old. Over the past 40-50 years, the frequency of lung abscesses has become about 10 times lower than before. The number of deaths has also decreased. In cases where there is a gram-negative microflora in the aspiration fluid, lethality can reach 20%.
According to the clinical and morphological form, the following processes are distinguished:
- gangrenous abscesses;
- purulent abscesses;
- gangrene of the lung.
According to the pathogenesis, destructive pneumonitis can be as follows:
- bronchogenic (postpneumonic, aspiration, obstructive);
- other (for example, suppuration may pass from nearby tissues).
Lung abscess is divided into the following forms:
- chronic (abscess lasts from 2-3 months).
Also, lung abscesses are primary and secondary. Primary ones are formed when the lung tissue dies in the process of damage to the lung parenchyma, this often happens with pneumonia. If the abscess is the result of a septic embolism or a breakthrough of an extrapulmonary abscess into the lung, then it is classified as secondary.
Lung abscesses can be unilateral or bilateral (affecting one or both lungs), as well as single or multiple. The following classification: central and peripheral. But such a division is not relevant for giant abscesses.
A huge number of microorganisms or their associations can cause infectious destruction of lung tissue. The causative agent of an abscess or gangrene of the lung can be anaerobes, aerobes, protozoa, mycobacteria, etc.
Destructive pneumonitis can develop only in the presence of factors that adversely affect the body’s defenses, and which create conditions for pathogenic microflora to enter the respiratory tract or aspiration. The most common risk factors are:
- drug overdose
- prolonged vomiting
- surgery under general anesthesia
- neurological disorders
- foreign bodies in the airways
- neoplasms in the lungs
- operations on the esophagus and stomach
- gastroesophageal reflux
The main process in the pathogenesis of lung abscess is aspiration. In some cases, there is also a bronchogenic origin that is not associated with aspiration, as well as the development of an abscess as a complication of pneumonia (the causative agent of the latter is more often staphylococci and streptococci). If the abscess cavity communicates with the bronchus, pus and dead tissue exit through the respiratory tract, which means that the abscess is emptying. Bronchogenic lung abscess develops when the wall of bronchiectasis is destroyed. In this case, the inflammatory process passes to the adjacent lung tissue from bronchoetase, an abscess is formed. The infection can also form an abscess. Infection can also spread, as occurs with subdiaphragmatic abscess and pleural empyema.
In the pathogenesis of lung gangrene, there is a weak manifestation of the processes of delimitation of necrotic lung tissue from healthy and a large intake of toxic products into the vascular bed. In patients over the age of 45, in a third of cases, the formation of an abscess is associated with a tumor.
At the beginning of the development of a lung abscess, the tissue becomes denser, since inflammatory infiltration is present. Later, purulent fusion appears in the center of the infiltrate; a cavity delimited from the adjacent tissue is formed. The abscess wall contains cellular elements of inflammation, fibrous and granulation tissues. An acute abscess with perifocal inflammatory infiltration of the lung tissue can become chronic with the formation of a dense pyogenic membrane. In the cavity of the abscess is liquid or pasty pus.
Gangrene from a pathomorphological point of view is characterized by massive necrosis, which has no obvious boundaries, passing into the nearby compacted and edematous tissue of the lung. Against the background of massive necrosis, multiple cavities of irregular shape are formed, which gradually increase and merge.
Symptoms and Diagnosis
First, the doctor collects an anamnesis, including possible risk factors. An abscess is formed over 10-12 days, during which the symptoms of the disease in most cases are due to pneumonia. At the beginning of the disease, weakness, malaise, cough with scanty sputum, chills are noted. Possible manifestations such as pain in the chest and coughing up blood.
Body temperature is often elevated. Even with small abscesses, there is shortness of breath, which is explained by intoxication of the body. These signs are even more pronounced if the patient has gangrene of the lung. The breakthrough of an abscess in the bronchus can be determined by the sharp release of fetid sputum in large quantities through the mouth. After that, the person’s condition becomes better, and the body temperature drops. With gangrene of the lung, sputum has a putrefactive character. An abscess produces 200-500 ml of sputum per day. With gangrene, the daily amount of sputum reaches one liter, in severe cases – more than a liter.