Diagnostic triad of pulmonary anthracofibrosis in spiral CT scan - a retrospective study

Anthracosis, a form of pneumoconiosis commonly caused by air pollution and other environmental factors, is a new entity in respiratory disorders. Bronchoscopy and transbronchial lung biopsy (TBLB) are the gold standard of diagnosis. Herein, we evaluated the results of bronchoscopy and chest computed tomography (CT) scans of 187 anthracotic patients.

Between April 2016 and April 2017, 187 cases (99 males, mean age 65 ± 10.2 years) who underwent flexible bronchoscopy and TBLB for various indications were considered for this study. CT examinations of these patients were reported as "blind to bronchoscopy results" by two experienced board-certified radiologists.

According to the results of bronchoscopy and TBLB, 100 patients were diagnosed as anthracotic. CT scans confirmed 71 of these cases as anthracosis. Sensitivity, specificity, PPV, NPV, and accuracy of hyperdense non-calcified mediastinal and hilar lymph nodes, known as "brilliant lymph nodes", compared to bronchoscopy were 55%, 92%, 89%, 64%, and 72%, respectively (CI: 95%). Also, there was a positive correlation between anthracosis and brilliant lymph nodes (p-value = 0). Analysis of hyper-attenuated lung with bronchoscopy estimated sensitivity, specificity, PPV, NPV, and accuracy gave 41%, 94%, 89%, 58%, and 65%, respectively (CI: 95%). The specificity of brilliant lymph nodes, hyper-attenuated lung, and multi-segmental atelectasis as a diagnostic "triad of anthracosis" was 100%.

Based on our analyses, the triad of brilliant lymph nodes, hyper-attenuated lung, and multi-segmental atelectasis was identified as a reliable set of imaging findings for the diagnosis of anthracosis.