Inorganic dust exposure produces variety of responses the complexity of which is not yet fully understood. Sarcoid like illness is well documented with beryllium and aluminum. Recently, an association is also observed between viterous fiber exposure and sarcoid like granulomatosis.13 Our case is an example of such type of illness secondary to man made mineral fiber (MMMF).
39 year old black male was working as a factory insulation installer for fifteen years.He had six months history of progressive exertional dyspnea, fatigue and occasional mild cough productive of white colored sputum. He denied fever, chills, night sweats, chest pain, hemoptysis, peripheral edema or orthopnea. Chest radiographs revealed diffuse alveolar opacities, bilateral apical cavitary lesions, bilateral granulomata, nodules and multiple calcified mediastinal lymph nodes. Transbronchial biopsy specimen showed non caseating foriegn body type granulomas. The foriegn bodies were polarized and scanning electron microscopy (SEM) identified them as silica, titanium, aluminum, chromium and nickel. In adddition peaks of magnesium, sulfur, potassium, calcium, phosphorus, copper and iron were also present.DISCUSSION: Production of artificial fiber has become a major industry since World War II. Fiber glass is used in acoustic and thermal insulation and has been implicated as a potential cause of fibrotic and granulomatous lung diseases.Several mechanism have been proposed for lung injury which include nonspecific accumulation of macrophages in alveoli with occasional granulomatous reaction4, production of hydroxyl radical resulting in DNA damage5, T-cell alveolitis and particle induced NF-kB stimulation. Drent et al. have demontrated presence of activated NF-kB in sarcoidosis as well.Three types of parenchymal responses have been identified with occupational dust exposure.These include interstitial fibrosis, nodular fibrosis and macule formation with emphysema.Stetter et al. studied lungs from 33 subjects who had no history of occupational exposure. All analysed lungs contained aluminum, silica, iron and titanium and some of them also had potassium, zinc, sulfur, magnesium and chromium.6Induction of disease by a foriegn particle depends on cumulative exposure, clearance an dissolution, latency, genetic susceptibility, biologic plausibility and interaction with host factors. Single occupational agent may cause many diseases because of differences in susceptibility and metabolism of individual or several agents may produce only one type of illness.An effective approach is to obtain a comprehensive lifetime occupational history. Material Safety Data Sheets will certainly be an asset to determine the chemical composition of commercial materials.Treatment is aimed to suppress inflammation in an attempt to halt disease process. Systemic corticosteroids may provide benefit in releiving symptoms2 but relapses are reported with steroid tapering. Long term efficacy of steroid therapy is unknown. Serial monitoring of pulmonary function testing can give an objective assessment of patient’s disease activity.Future harmful exposure should be avoided and to prevent further occurrences employer should be notified with patient’s permission.
In conclusion, widespread deposition of foriegn particles found in MMMF have contributed to the disease process in this patient. Data pertaining to epidemiology, presentation, prognosis and treatment is inadequate. Further studies are needed to focus these issues in future.
G.T. Farooqui, None.