Etiology and routes of infection spread
According to their origin and mechanism of development, abscesses are divided into five main groups:
- Post-pneumonic. They occur as a complication of acute pulmonary inflammations, including suppuration of a pulmonary infarction zone.
- Bronchogenic (aspiration). They form as a result of the aspiration of foreign agents and the development of necrotizing pneumonia.
- Hematogenous (metastatic). They are associated with the seeding of septic emboli via the bloodstream. The source can be distant foci in osteomyelitis, pelvic inflammatory diseases, thrombophlebitis, or infective endocarditis.
- Traumatic. They develop against the background of penetrating chest wounds or severe contusions.
- Contact. They result from the spread of purulent inflammation from adjacent structures, for example, in empyema of the pleura or subdiaphragmatic abscess.
Among the bacterial flora, Staphylococcus, Klebsiella, and Streptococcus predominate, whereas mycoplasmas and fungal pathogens are significantly less common. A key pathogenetic factor is the blockage (obstructive) of the draining bronchus by vomit, a foreign body, or a growing tumor.
High-risk groups for abscess formation include individuals with significantly compromised immunity: elderly patients, people with alcohol dependence, AIDS patients, as well as patients in the post-anesthetic period and those receiving cytostatics.
Clinical presentation and stages of the disease
Clinical manifestations directly depend on the condition of the draining bronchus—the presence or absence of a connection between the purulent cavity and the bronchial tree.
- Pre-rupture period (closed abscess). The patient's condition is assessed as severe. Purulent intoxication syndrome comes to the fore: high hectic fever accompanied by profuse sweating is observed. Complaints of chest pain are possible. A blood test reveals pronounced leukocytosis with a left shift of the leukocyte formula.
- Post-rupture period (open abscess) into the bronchus. At the moment when the abscess finds an outlet into the bronchial tree, there is a sharp improvement in well-being and normalization of body temperature. The cough becomes productive: foul-smelling purulent sputum, often with streaks of blood, is discharged in large volumes—literally "a mouthful."
Complicated courses pose a particular danger when a subpleurally located abscess ruptures not into the bronchus, but into the pleural cavity. In this case, massive absorption of decay products by the pleural leaves occurs, causing a sharp increase in intoxication and creating a high risk of acute vascular failure.
Physical and instrumental diagnostics
When examining a patient, especially if the focus is large and located subpleurally, classical signs of pulmonary consolidation syndrome are detected.
- Inspection: noticeable lag of the affected half of the chest during breathing.
- Percussion: until the abscess is emptied, dull percussion sound is determined over the lesion zone. After the contents are released and the cavity fills with air, dullness is replaced by tympanitic sound.
- Auscultation: bronchial breathing is heard. After the connection with the bronchus is established, various moist rales appear.
- X-ray examination: allows tracking the dynamics of the process. At the initial stage, the infiltrate stage is visualized, then a cavity forms. The appearance of a cavity with a distinct horizontal fluid level is a pathognomonic sign of an abscess.
- Laboratory methods: neutrophilic leukocytosis with a left shift and an accelerated ESR are detected in the blood. Sputum analysis confirms its purulent nature, unpleasant odor, and the presence of blood impurities.
Principles of treatment
Therapeutic tactics are divided into two main areas.
Conservative treatment includes massive antibiotic therapy, the drugs for which are selected with mandatory consideration of the sensitivity of the isolated microflora. The most critical component is ensuring adequate pus drainage: drainage enhancement methods are used, such as postural drainage (treatment with a special body position) and therapeutic bronchoscopy.
Surgical treatment is indicated in cases where conservative antibiotic therapy proves ineffective. Surgical intervention is also necessary when the process becomes chronic (formation of an encysted abscess), life-threatening complications develop (e.g., massive pulmonary hemorrhage), or when a tumor nature of the detected formation is suspected.
Briefly: answers to topical questions
What diseases require differential diagnosis of lung abscess?
Differential diagnosis of lung abscess is carried out with cavity formations in the lung that have a similar radiological picture.
| Disease | Differential diagnostic features |
|---|---|
| Decaying peripheral lung cancer (cavernous form) | Cavity with uneven, often "eaten-away" contours. |
| Tuberculous cavity | Walls are usually thinner; horizontal fluid level is less common or less pronounced. |
| Suppurating lung cyst | Listed as a condition from which lung abscess should be differentiated. |
| Echinococcal cyst | Listed in instrumental differential diagnosis during chest CT. |
Thick cavity walls, a pronounced horizontal fluid level, and an acute clinical presentation favor a lung abscess.
For quick memorization of the etiological classification, use the acronym "PB-GTC": Post-pneumonic, Bronchogenic, Hematogenous, Traumatic, Contact.
Class and exam questions
How does the nature of the cough change when the pathology transitions to the second stage?
After the rupture of the abscess into the bronchus, the cough becomes sharply productive. The patient begins to cough up large volumes of foul-smelling purulent sputum ("by the mouthful"), often mixed with blood.
Why do percussion findings change after the abscess is emptied?
In the closed stage, the cavity is filled with dense purulent masses, which gives a dull sound. After drainage through the bronchus, the pus exits, the cavity fills with air, and the percussion sound becomes tympanitic.
What radiological picture is most typical for this pathology?
A pathognomonic sign, i.e., the most reliable sign of a formed abscess, is the presence of a radiolucent cavity with a horizontal fluid level on the radiograph.
What else to study on this topic
- Morphological structure of the capsule: features of the formation of granulation and fibrous layers.
- Mechanisms of development of acute vascular failure during the rupture of an abscess into the pleural cavity.
- Differential diagnosis of malignant tumor growth and suppurative process.
- Specifics of the technique for postural drainage and therapeutic diagnostic bronchoscopy.
- Features of the microbiological picture in abscess formation against the background of HIV infection and cytostatic therapy.
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