Environmental, Inhaled and Ingested Causes of Pulmonary Fibrosis

Abstract

Pulmonary fibrosis is a general term that refers to a collection of connective tissue around alveolar structures. There are over 200 disorders where the lungs may be involved in a fibrotic response. To determine the cause of pulmonary fibrosis requires an in depth understanding of the pathogenesis of pulmonary fibrosis and breadth of knowledge of the causative agents and associated disorders that may lead to pulmonary fibrosis. A comprehensive evaluation of the patient is absolutely essential, starting with detailed history that includes an occupational and environmental history because fibrogenic exposures can occur in many settings. Equally important is a history of ingestion of pharmaceutical or nonpharmaceutical substances. A physical examination and judicious investigations are always a part of any comprehensive clinical assessment but they are not commonly helpful in elucidating the cause of most pulmonary fibrotic disorders. Although, a chest film is invariably done, a logical and strongly recommended next step is a high-resolution computed tomography (HRCT). HRCT provides a better assessment of the radiological pattern, may suggest a diagnosis as well as direct the site, and type of lung biopsy. If the history and investigations do not lead to a diagnosis then a lung biopsy is required. Prevention or removal of the inciting agent is critical to the treatment of these disorders and in some instances corticosteroids may be of help.

Pulmonary fibrosis after high cumulative dose nitrosourea chemotherapy in a cat

“…Elastosis, alveolar cuboidalization, emphysema, Masson’s bodies and granuloma formation are also reported 12,14,15 . In humans, drug‐induced pulmonary fibrosis may be histologically indistinguishable from other causes of fibrosis 16 …”

“…12,14,15 In humans, drug-induced pulmonary fi brosis may be histologically indistinguishable from other causes of fi brosis. 16 Pulmonary toxicity was fi rst noted during nitrosourea drug development when fi brosis developed in the lungs of dogs treated experimentally with BCNU. 17 Information on the drug dose and dosing interval used in these experiments is not available, however.…”

Idiopathic Pulmonary Fibrosis—an Epidemiological and Pathological Review

“…A latency period of a decade or more is consistent with findings in other ILDs with known causes. For example, symptoms in subjects with asbestosis occur typically approximately 15 years after initial exposure [5], while chronic silicosis occurs approximately 10 years after exposure [13]. Patients with IPF generally experience a decline in lung function, which often progresses slowly, but inexorably over years, resulting in scarring, pulmonary failure, and death.…”

Potential pathogenic bacteria in metalworking fluids and aerosols from a machining facility

“…The interest in bacterial exposures to metalworking personnel has intensified because an outbreak of hypersensitivity pneumonitis was linked to high concentrations of bacteria in metalworking fluid (Wallace et al , 2002). Hypersensitivity pneumonitis is a pulmonary disorder involving an immunologic reaction of the lung to inhaled sensitizing agents of organic origin, such as bacterial or fungal antigens within aerosols (Bernstein et al , 1995; Khalil et al , 2007). To cause such an immunological response, the bacterial cell does not have to be viable.…”