Inflammation Progresses to Normal Tissue in Patients with Anthracosis after Discontinuation of Exposure to Fossil Fuel.

Background: Exposure to toxic materials predisposes the lungs to infectious agents and inflammatory responses. The present study was performed on patients with anthracosis caused by exposure to fossil fuels in previous years, and histopathological features of airways' normal-appearing tissue were compared with histopathological features of anthracotic plaques in these patients.

Methods: Bronchoscopic evaluations were performed on bakery workers who were directly in contact with fossil fuels. Samples were taken from anthracotic plaques (Group A) or seemingly intact tissues at their periphery (Group B). Pathological evaluations were done after hematoxylin and eosin staining. Then, microbiological cultures were performed for the diagnosis of . Data obtained from bronchoscopy, pathology, and cultures were compared between anthracotic and normal-appearing peripheral tissues using chi-square and analysis of variances (ANOVA) at a 95% confidence level.

Results: Sixty-eight patients were diagnosed with anthracotic plaques. The mean ± SD of the patients' age was 72.12 ± 13.74 years. Females comprised 58.8% of the sample, and 85.3% of the patients were Iranian. The frequency rates of disseminated plaques and obstructive types were 86.8% and 48.5%, respectively. Ten patients (14.70%) were diagnosed with tuberculosis, and 4.41% (3 of 68) had granuloma, which was detectable only in samples gathered from Group A. Fibrosis was more common in Group A (10.3%,  = 0.03), and most of the evaluated samples in both groups exhibited inflammatory features.

Conclusion: Inflammatory changes and tissue damage can be seen in anthracotic plaques and the surrounding normal-appearing tissue, even after removing the triggering factors. So, it is suggested to take a biopsy from seemingly intact tissue at the periphery of the anthracotic plaque when a biopsy is needed in a patient with anthracosis to reduce the risk of bleeding. Besides, medical treatment should be done to control inflammation.