Thoracic involvement in Erdheim-Chester disease: computed tomography imaging findings and their association with the BRAF ^V600E mutation

Objectives: To investigate the computed tomography (CT) thoracic findings in Erdheim-Chester disease (ECD) and evaluate the association of these findings with the BRAF ^V600E mutation. Methods: This was a prospective study of patients with ECD (n=61, men=46) who underwent thoracic CT imaging. CT examinations were independently interpreted by two experienced radiologists. Association of imaging findings with BRAF ^V600E was achieved via the Chi-square or Fisher’s exact test and odds ratios (OR) with 95% confidence intervals (CI), as appropriate. Results: Fifty-five ECD patients (90%) showed pulmonary findings, which included interlobular septal thickening (69%), pulmonary nodules (62%), airway thickening (13%) and ground glass opacities (36%). Pulmonary nodules were classified by the pattern of distribution: subpleural regions (36%), lung parenchyma (13%) and both regions (13%). Pleural and mediastinal involvement were present in 15% and 62% of cases, respectively. The most common mediastinal finding was sheathing of the right coronary artery (34%), followed by sheathing of the thoracic aorta (30%). The BRAF ^V600E mutation, positive in 31 patients, was associated with the frequency of sheathing of the coronary arteries (p = 0.01). Conclusions: Of the thoracic findings reported in this study, we found a statistically significant positive association between the BRAF ^V600E mutation and presence of coronary artery sheathing. Key Points: • To assess the degree of thoracic involvement in ECD with CT. • BRAF ^V600E mutation has a high association with right coronary artery sheathing. • BRAF ^V600E genetic testing detects patients at high risk of developing RCA sheathing.