Usual interstitial pneumonia (UIP) pattern in pulmonary sarcoidosis

<bold>Background:</bold> Although uncommon, the radiological pattern of usual interstitial pneumonia (UIP) is a well-defined phenotype in pulmonary sarcoidosis. The disease behaviour of pulmonary sarcoidosis patients with UIP pattern has not yet sufficiently been evaluated. <bold>Aim:</bold> To evaluate the baseline characteristics and functional disease behaviour of sarcoidosis patients with UIP pattern on chest CT scan. <bold>Methods:</bold> We retrospectively identified 29 biopsy-proven pulmonary sarcoidosis patients presenting with UIP pattern in the Royal Brompton Hospital Sarcoidosis Database between 2003 and 2023. Concurrent pulmonary function tests (PFT) were assessed at baseline and after 1, 2 and 5 years. <bold>Results:</bold> The sarcoidosis-UIP patients were mainly male(69%), Caucasian in origin(52%) and non-smokers(62%). UIP pattern was discovered at 62(58,67)years old and after 11(3,21)years from sarcoidosis diagnosis. Baseline PFTs showed a mildly impaired FVC (70(59,91)%) and a moderate DLCO impairment (41(27,49)%). A total of 23(79%) patients were on treatment at baseline (48% steroids, 4% 2nd-line immunosuppressants, 43% combination). All patients were followed up for a median time of 4(2,8)years. A total of 23, 9 and 4 patients remained stable after 1, 2 and 5 years respectively, while, 6, 8 and 7 patients experinced a decline in FVC >5%. Median FVC decline for patients declining >5% was 370(300,487)mL, 240(200,305)mL and 280(265,470)mL after 1, 2 and 5 years respectively. <bold>Conclusion:</bold> UIP pattern is usually associated with a progressive fibrotic phenotype. Nevertheless, significant stability was noted in our sarcoidosis-UIP population over 5 years. This may be associated with both the disease behaviour as well as immunosuppressive treatment.