Comparison of Fibrotic Sarcoidosis with Usual Interstitial Pneumonia

Abstract

Objectives: This retrospective study examines the differences of the fibrotic stage of sarcoidosis with idiopathic interstitial fibrosis using High-resolution Computed Tomography (HRCT), imaging features and quantification of the severity and extent of the disease. Methods: 81 patients with biopsy diagnosed pulmonary sarcoidosis and 81 patients with usual interstitial pneumonia (UIP) were included. All underwent HRCT scan. Findings were evaluated per lung lobe. The severity of disease was quantified per feature and overall with the Gay - Watters score. Results: Respectively, the two groups recorded: 52 (64.20%) vs 60 (74.07%) presented a reticular pattern, 62 (76.54%) vs 74 (91.36%) thickened septal lines, 24 (29.63%) vs 56 (69.14%) honeycomb pattern, 52 (64.20%) vs 43 (53.09%) ground glass attenuation, 7 (8.64%) vs 27 (33.33%) ground glass with traction bronchiectasis, 47 (59,26%) vs 25 (30.86%) micronodular pattern, 48 (60,49%) vs 1 (1.23%) hilar / mediastinal lymph node enlargement. The micronodular pattern showed a statistically significant association with sarcoidosis (p = 0.03), whereas ground glass opacities associated with bronchiectasis was statistically significant for UIP (p = 0.0021). Honeycomb was statistically significant for UIP (P = 0.0037). Lymph node enlargement was associated with sarcoidosis (p = 0.0001). Thickened septal lines seemed to be more frequent with UIP compared to sarcoidosis (p = 0.05). Overall, the severity of parenchymal involvement for sarcoidosis and UIP was 26 ± 19 / 43 ± 18 respectively (p < 0.001). Conclusions: The micronodular pattern highly indicates sarcoidosis, whereas honeycombing and ground glass with traction bronchiectasis are associated with UIP. These features can assist on differentiation, when disease presents itself with fibrotic HRCT characteristics at diagnosis.