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Toxic fibrosing alveolitis: causes, symptoms, diagnosis, treatment

Alexey Portnov, medical expert
Last reviewed: 20.11.2021

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Toxic fibrosing alveolitis is a form of fibrosing alveolitis due to the effect on the parenchyma of light substances with cytotoxic properties.

Causes of toxic fibrosing alveolitis

Toxic fibrosing alveolitis is caused by two groups of factors - drug chemotherapy and industrial toxic substances. Toxic fibrosing alveolitis can be caused by the following medicinal substances:

alkylating cytotoxic drugs: chlorbutin (leukeran), sarcolysin, cyclophosphamide, methotrexate, myelosan, 6-mercaptopurine, cytosine-arabinoside, carmustine, 5-fluorouracil, azathioprine;
antitumor antibiotics: bleomycin, mitomycin-C;
cytostatics obtained from medicinal plants: vincristine, vinblastine;
other antitumor drugs: procarbazine, nitrosomethylurea, thioguanoside, uracil-mastard;
antibacterial agents: derivatives of nitrofuran (furazolidone, furadonin); sulfonamides;
antifungal drugamphotericin B;
antihypertensive agents: apressin, anaprilin (obzidan, inderal and other beta-blockers);
antiarrhythmics: amiodarone (cordarone), tokainid;
enzymatic cytotoxic drug L-asparaginase;
oral hypoglycemic drug chlorpropamide;
oxygen (with prolonged inhalation).

To toxic industrial substances that cause toxic fibrosing alveolitis, include:

irritating gases: hydrogen sulphide, chlorine, carbon tetrachloride, ammonia, chloropicrin;
vapors, oxides and metal salts: manganese, beryllium, mercury, nickel, cadmium, zinc;
chlorine and organophosphate insectophangicides;
plastics: polyurethane, polytetrafluoroethylene;
nitrogases, formed in mines, silos.

The frequency of development of toxic fibrosing alveolitis depends on the duration of the drug and its dose and on the duration of the action of the production toxic factor.

Pathogenesis

The main pathogenetic factors of toxic fibrosing alveolitis are:

defeat of the microcirculatory bed of the lungs (necrosis of the capillary endothelium, microthrombosis, ruptures and desolation of capillaries);
interstitial edema, hyperproduction of connective tissue fibers, thickening of interalveolar septa;
necrosis of type I alveolocytes and metaplasia of type II, disruption of surfactant production, alveolar dissolution;
development of type III immunological reaction (formation of antigen-antibody complexes).

Thus, in the development of toxic fibrosing alveolitis, the most immediate effect is the direct toxic effect of drugs and harmful production factors on lung tissue, as well as the development of type III immunological reaction. Ultimately, interstitial and intraalveolar fibrosis of the lungs develops.

Symptoms of toxic fibrosing alveolitis

The clinical picture of toxic fibrosing alveolitis, lung radiological data, spirography are similar to those in exogenous allergic alveolitis. The leading clinical sign is dyspnoea, which becomes steadily progressing with the continued impact of the causative agent - drug or production toxic substances. Three forms of toxic fibrosing alveolitis are distinguished along the course: acute, subacute and chronic. Symptomatology is the same as in exogenous allergic alveolitis.