Lipoid pneumonia is an inflammatory infiltration of the lungs that develops due to inhalation or endogenous accumulation of lipid–containing substrates. Clinical manifestations include weakness, fever, chest pain, dyspnea, dry cough, hemoptysis. The pathological process is verified by radiography and CT of the lungs, bronchoscopy with BAL analysis, histology of biopsy material. To resolve pneumonia, corticosteroid therapy, oxygen support, bronchodilator therapy are performed, with a complicated course – antibiotic therapy.
J69.1 Pneumonitis caused by inhalation of oils and essences. Fatty pneumonia
Lipoid (fatty) pneumonia is a peculiar reaction of the pulmonary parenchyma (inflammation with the outcome of fibrosis) to the accumulation of fatty substances in the alveoli. It is rarely detected in vivo, according to autopsy data – in 1-2.5% of cases, although in risk groups the prevalence can reach more than 14%. For the first time, nosology was reported in 1925 by pathologist G.F. Laflin, who discovered fatty inclusions in the lung tissue of four patients who had taken oil laxatives and nasal drops for a long time during their lifetime. In modern pulmonology, gasoline pneumonia is a type of acute exogenous lipoid pneumonia.
Causes of lipoid pneumonia
According to the etiological structure, exogenous and endogenous lipoid pneumonia are distinguished. The exogenous form is associated with the inhalation or aspiration of fatty substances and mineral oils, which, deposited in the alveoli, trigger an inflammatory reaction. The most frequent triggers are:
- mineral oils (paraffin, petroleum jelly);
- petroleum products (kerosene, gasoline);
- vegetable and animal oils and fats (olive, sunflower, ghee, squalene).
These and other substrates are sometimes used for independent medical procedures (nasal lubrication, instillation into the tracheostomy, reception as laxatives). Also, the inhalation of oil-containing aerosols is common among people of professions such as painters, firefighters, agricultural and metalworking workers, fakir magicians blowing fire out of their mouths.
Endogenous lipoid pneumonia is caused by the accumulation of exudate in the lung tissue, rich in cell breakdown products containing cholesterol, triglycerides, lipids. This way of developing fatty pneumonia is typical for:
- obstruction of the bronchus by a foreign body;
- obstructing bronchial central lung cancer;
- disorders of lipid ‒ lipidosis transport;
- invasive pulmonary mycoses.
There are certain population groups, conditions and concomitant diseases that increase the risk of developing lipoid pneumonia. The age groups at risk include infants, patients over 50 years of age, workers engaged in the production of petrochemical products. Predisposing background for aspiration of oily substances are:
- gastroesophageal reflux;
- tracheopesophageal fistula;
- congenital cleft of the hard palate;
- the presence of a tracheostomy;
- mental disorders;
- alcohol consumption.
The severity and prevalence of pathological changes in exogenous lipoid pneumonia depends on the nature, quantity, and time of exposure to the etiological agent. Fatty substances are able to inhibit the cough reflex to a certain extent and reduce the mucociliary function of the bronchial epithelium, which facilitates their entry into the respiratory tract. Lipid-containing substances fill the lumen of the bronchioles and alveoli, causing local pro-inflammatory effects.
When inhaling (aspiration) of vegetable and mineral oils, the inflammatory reaction is weakly expressed. With a single or time-limited contact with a pathogenic agent, fat droplets are encapsulated with the formation of a paraffinoma delimited by fibrous tissue. With repeated or massive inhalation, diffuse pulmonary consolidation (opechenia) occurs.
Animal oils and fats cause more pronounced changes due to lipase hydrolysis in the lungs with the release of free fatty acids. The latter initiate a powerful inflammatory process with local edema and intraalveolar hemorrhages. In the future, fatty acids undergo phagocytosis by alveolar macrophages, as a result of which the cytoplasm of these cells is filled with fatty inclusions. Lipid–saturated macrophages – lipophages – settle and accumulate in the interalveolar septa, causing their thickening and destruction. In the outcome of lipoid pneumonia, pulmonary fibrosis develops with a decrease in the area of the functioning parenchyma.
With an endogenous mechanism, lipid-laden macrophages and cellular decay products accumulate in the alveoli below the bronchial obstruction site. Nonspecific interstitial pneumonia develops. Pathomorphologically, lipoid pneumonia is an aseptic inflammatory process with the presence of macrophages and giant cells loaded with lipid molecules in the aspirate and biopsy.
According to the etiology, lipoid pneumonia can be endogenous and exogenous:
- endogenous – occurs when its own lipid fractions are destroyed and deposited in the alveoli;
- exogenous – develops with inhalation / aspiration intake of fatty components from the external environment.
Acute course of lipoid pneumonia is observed with a single massive inhalation / aspiration of a fatty substrate. The chronic variant develops with repeated and prolonged ingestion of small amounts of oil aerosols into the respiratory tract. Cases are described when pathological processes developed in terms from 1 month to 10 years.
Lipoid pneumonia symptoms
An acute exogenous variant of pathology is characterized by a sudden onset. Worries about a feeling of lack of air, shortness of breath at rest, unproductive cough, chest pain. In the anamnesis, you can trace the recent inhalation or ingestion of oil-containing substances. In mild cases, all clinical manifestations are resolved against the background of cessation of contact with triggers and symptomatic treatment.
Chronic lipoid pneumonia is asymptomatic or with nonspecific complaints of weakness, dry cough, shortness of breath with minimal exertion, discomfort in the chest. In rare cases, hemoptysis, weight loss, fever are noted. Over time, chronic respiratory failure develops.
Complications of lipoid pneumonia
With massive ingestion of fatty agents into the respiratory tract, respiratory distress syndrome develops. The patient may die from acute respiratory failure and pulmonary edema. The course of lipoid pneumonia can be complicated by pleurisy, pneumothorax, mediastinal emphysema, secondary microbial or fungal infection. The chronic variant is accompanied by the formation of pneumofibrosis, pulmonary hypertension and chronic pulmonary heart disease.
When examining a patient with these complaints, it is important to find out the previous anamnesis: intake or inhalation of fat-containing substances, the frequency and duration of contact. During examination and auscultation, a pulmonologist can detect an increase in BPD, dry wheezing on both sides, crepitation. Further diagnostic tactics include:
- Chest CT scan. X-ray examination reveals a bilateral segmental or fractional decrease in pneumatization of lung tissue (a symptom of “frosted glass”), thickening of interlobular partitions (a symptom of “cobblestone pavement”). In the later stages, areas of fibrosis and compaction of the interlobular pleura are visible.
- Bronchoscopy. The purpose of bronchial tree endoscopy is to exclude obstruction, to take bronchoalveolar lavage (BAL) and to conduct a trans-bronchial biopsy. During cytological examination of the ball and sputum, histology of the biopsy, lipophages are detected.
- FER. The study is carried out with a satisfactory condition of the patient and the absence of a tracheostomy. Spirometry may reveal moderate obstructive pulmonary ventilation disorders, a decrease in the diffusion capacity of the lungs.
- Saturation monitoring. It is carried out in an invasive (determination of blood gas composition) and non-invasive way (pulse oximetry). In patients with lipoid pneumonia, the decrease in blood oxygen saturation depends on the degree of lung damage.
Lipoid pneumonia has non-specific symptoms and an X-ray picture, therefore, the following nosologies are excluded when making a diagnosis:
- cryptogenic organizing pneumonia;
- bacterial and fungal pneumonia;
- aspiration pneumonia;
- covid pneumonia;
- bronchoalveolar lung cancer;
- alveolar proteinosis;
- Wegener’s granulomatosis.
Treatment for lipoid pneumonia
The first condition for successful treatment is the cessation of aerosol intake of lipid-containing agents into the respiratory tract and the elimination of bronchial obstruction. In asymptomatic lipoid pneumonia, additional therapy is not prescribed. In cases requiring hospitalization is carried out:
- Pharmacotherapy. Pathogenetic therapy consists in the appointment of infusions of corticosteroids (sometimes in combination with their inhalation) and subsequent transfer to oral form. Mucolytics are also used, and antibiotics are used in the development of nosocomial pneumonia.
- Sanation bronchoscopy. Repeated bronchoalveolar lavage procedures are indicated to remove fat droplets and lipophages from the respiratory tract. The effectiveness of therapeutic bronchoscopes is the higher, the less time has passed since the aspiration or inhalation of fatty substances.
- Bronchodilator therapy. It includes percussion chest massage, physical therapy, postural drainage, breathing exercises. Helps to accelerate the evacuation of fat molecules from the lower respiratory tract.
- Oxygen support. At low saturation, oxygen therapy can be performed through a nasal catheter or a facial mask. In some cases, it may be necessary to install a tracheostomy cannula, intubation and ventilation.
Prognosis and prevention
The scenario of the development and outcome of the disease depends on the causes of lipoid pneumonia, the dose and duration of exposure to the pathogenic agent. Acute exogenous forms caused by a single contact can be resolved independently. Chronic forms end with the formation of pulmonary fibrosis, which restricts respiratory function. With a burdened course, fatal outcomes are not excluded. The prognosis of endogenous lipoid pneumonia is directly related to the course of the underlying disease.
Prevention consists in the careful use of fat-containing medicines and cosmetics, the use of respiratory protection in the workplace. It is advisable to restrict access to dangerous substances to children, persons with swallowing disorders, mental disorders, alcohol dependence.
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