Frequency of computed tomography signs of mosaic attenuation present according to “2011 ATS criteria”# or “current ATS/FS criteria”¶ thresholds for fibrotic hypersensitivity pneumonitis (FHP) as an alternative diagnosis to idiopathic pulmonary fibrosis (IPF)
| IPF | FHP | p-value | |
| Patients | 57 | 45 | |
| Preserved lobules | |||
| 2011 ATS criteria | 11 (19.3) | 27 (60.0) | <0.001 |
| Current ATS/FS criteria, ≥3 lobules | 4 (7.0) | 15 (33.3) | <0.001 |
| Current ATS/FS criteria, ≥5 lobules | 1 (1.8) | 8 (17.8) | 0.01 |
| Low-density lobules | |||
| 2011 ATS criteria | 29 (50.9) | 35 (77.8) | 0.005 |
| Current ATS/FS criteria, ≥3 lobules | 8 (14.0) | 23 (51.1) | <0.001 |
| Current ATS/FS criteria, ≥5 lobules | 2 (3.5) | 7 (15.6) | 0.04 |
| Headcheese sign | |||
| 2011 ATS criteria | 4 (7.0) | 22 (48.9) | <0.001 |
| Current ATS/FS criteria, ≥3 lobules | 4 (7.0) | 22 (48.9) | <0.001 |
| Current ATS/FS criteria, ≥5 lobules | 2 (3.5) | 19 (38.8) | <0.001 |
| Expiratory air trapping | |||
| 2011 ATS criteria | 26 (45.6) | 37 (82.2) | <0.001 |
| Current ATS/FS criteria, ≥3 lobules | 5 (8.8) | 22 (48.9) | <0.001 |
| Current ATS/FS criteria, ≥5 lobules | 1 (1.8) | 9 (20.0) | 0.004 |
Data are presented as n or n (%), unless otherwise stated. #: 2011 American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society (JRS)/Latin American Thoracic Association (ALAT) guidelines [4]; ¶: 2018 ATS/ERS/JRS/ALAT guidelines [5]/2017 Fleischner Society White Paper [6]. Frequency of various computed tomography signs of mosaic attenuation by diagnosis, using different definitions of mosaic attenuation and different thresholds of mosaic attenuation for FHP based on guidelines. “2011 ATS criteria” requires at least one lobule in three or more lobes, bilaterally. “Current ATS/FS criteria, ≥3 lobules” requires three or more lobules in three or more lobes bilaterally. “Current ATS/FS criteria, ≥5 lobules” requires five or more lobules in three or more lobes bilaterally. Headcheese represents the sum of both low-density lobules and preserved lobules only when both are present in the same lobe. p<0.05 was considered significant.