Published in:
01-06-2020 | Hypersensitivity Pneumonitis | Original Article
High-resolution CT features distinguishing usual interstitial pneumonia pattern in chronic hypersensitivity pneumonitis from those with idiopathic pulmonary fibrosis
Published in: Japanese Journal of Radiology | Issue 6/2020
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Purpose
Radiologic diagnosis of chronic hypersensitivity pneumonitis (CHP) presenting a usual interstitial pneumonia (UIP) pattern is challenging. The aim of this study was to identify the high-resolution CT (HRCT) findings which are useful to discriminate CHP–UIP from idiopathic pulmonary fibrosis (IPF).
Materials and methods
This study included 49 patients with well-established bird-related CHP–UIP, histologically confirmed, and 49 patients with IPF. Two groups of observers independently assessed HRCT, evaluated the extent of each abnormal HRCT finding. When their radiological diagnosis was CHP–UIP, they noted the HRCT findings inconsistent with IPF.
Results
Correct CT diagnoses were made in 79% of CHP–UIP and 53% of IPF. Although no apparent difference was seen in the extent of each HRCT finding, upper or mid-lung predominance, extensive ground-glass abnormality, and profuse micronodules were more frequently pointed out as inconsistent findings in CHP–UIP than IPF (p = 0.007, 0.010, 0.001, respectively). On regression analysis, profuse micronodules [OR 13.34 (2.85–62.37); p = 0.001] and upper or mid-lung predominance of findings [OR 2.86 (1.16–7.01); p = 0.022] remained as variables in the equation.
Conclusion
In this cohort, some IPF cases were misdiagnosed as CHP–UIP. Profuse micronodules and upper or mid-lung predominance are important clues for the differentiation of CHP–UIP from IPF.