Original Article Anthracotic Pigment in Transbronchial Lung Biopsy: An Innocent Bystander or Pathogenic Agent for Parenchymal Lung Disease Apoorva Pandey 1 , Ritu Kulshrestha 1 , Balakrishnan Menon 2 , Raj Kumar 2 and S.N. Gaur 2 Departments of Pathology 1 and Pulmonary Medicine 2 , Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India Abstract Background. Anthracosis has been recently identified as a cause of bronchitis and bronchial stenosis in both developing and developed countries in the world. However, its exact nature whether as an innocent bystander or pathogenic agent for parenchymal lung disease is unknown. Methods. We retrospectively analysed 384 transbronchial lung biopsies (TBLBs) received at Department of Pathology over a seven-year period (August 2010 to August 2016). Thirteen TBLBs showed normal lung parenchyma were taken as controls; 32 (8.3%) TBLBs showed deposition of anthracotic pigment, with or without fibrosis and were further studied. Masson-Trichrome and Ziehl-Neelsen stains were used to confirm the diagnosis of fibrosis and tuberculosis, respectively. Results. The TBLBs were histopathologically categorised into: Group 1 normal lung parenchyma, (controls, n=13, 3.4%); Group 2: pigment deposition with fibrotic parenchymal reaction (n=11, 34.4%); Group 3: pigment deposition with inflammatory parenchymal reaction (n=11, 34.4%); and Group 4: pigment deposition with granulomatous parenchymal reaction (n=10, 31.3%). In two cases of Group 2 and one case of Group 3, parenchymal deposits of silicate crystals were also identified by polarising microscopy. Conclusions. Anthracosis does not appear to be an innocent bystander and needs to be meticulously assessed for its role as pathogenic agent for parenchymal lung disease in all cases. Our observations suggest that identifying the pigment deposited and correlation with the underlying pathology in the limited tissue sample available can help in reaching a definitive diagnosis. [Indian J Chest Dis Allied Sci 2018;60:27-31] Key words: Anthracosis, Bronchial anthracofibrosis, Granulomatous inflammation, Transbronchial lung biopsy. [Received: October 27, 2016; accepted after revision: July 26, 2017] Correspondence and reprint requests: Dr Ritu Kulshrestha, Assistant Professor, Department of Pathology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi-110 007, India; E-mail: ritukumar71@yahoo.com Introduction Anthracosis is the deposition of coal/carbon particles and other black pigments in the lungs. It is found in heavy smokers, in city dwellers exposed to high environmental particulate matter and after occupational exposures to coal. This condition has been traditionally associated with pneumoconioses 1 and was initially reported in mummies. 2,3 Chung et al, 4 retrospectively analysed the Korean patients with anthracotic pigment deposition, focal mucous fibrosis and bronchial stenosis and termed this distinct clinical entity as “bronchial anthracofibrosis”. A predominance of anthracofibrosis was later identified in elderly non-smoking women with a long standing history of exposure to wood smoke used for cooking. 5 These patients usually present with chronic cough, exertional dyspnoea and other constitutional symptoms that may be similar to bronchogenic carcinoma and endobronchial tuberculosis (TB). The bronchial narrowing with distal atelectasis seen on radiology further adds to the diagnostic dilemma. Adding to the above is the recognition that anthracotic pigment can co-exist with granulomatous infections, such as TB, malignancy and biomass fuel exposure, emphasising the need for accurate tissue diagnosis. 6 Recent studies 7,8 from India have attempted to study the association of anthracosis with demographic variables, biomass fuel, and occupational exposure. These studies revealed that 60% cases of anthracosis have been diagnosed with either old or active pulmonary TB. However, these observations are in contrast to another study 8 in which no relationship was found between anthracosis and TB. Therefore, relationship between these diseases needs to be further studied. Transbronchial lung biopsy (TBLB) is a commonly used technique for ascertaining tissue diagnosis in pulmonary diseases. It is limited by the small size of the biopsy and the centrilobular location of the tissue obtained. While interpreting the anthracotic