Sarcoidosis and IPF in the same patient-a coincidence, an association or a phenotype?

Abstract Background Idiopathic Pulmonary Fibrosis (IPF) and Sarcoidosis are distinct clinical entities. Fibrotic disease in pulmonary sarcoidosis is typically upper lobe predominant. In IPF fibrosis is basilar and peripheral predominant [usual interstitial pneumonia (UIP) pattern]. Sarcoidosis and UIP have rarely been observed in the same patient. We sought to characterize patients manifesting both sarcoidosis and IPF and compare clinical features and survival to that of patients with “Lone-IPF” (IPF only) and pulmonary sarcoidosis with fibrosis in a non-UIP pattern. Methods Patients were identified from a clinical database and data abstracted from medical records (1995–2016): 1) 25 patients with combined sarcoidosis and IPF (CSIPF) defined by clinical and histological features of sarcoidosis and HRCT features of possible or definite UIP or UIP by histopathology; 2) Randomly selected control patients during the same period: 28 Lone-IPF, 25 stage III/IV pulmonary sarcoidosis. Results The gender and race of patients with CSIPF and Lone-IPF patients were similar (68% male and 84% Caucasian), as were survival outcomes. Mean time from IPF diagnosis to death: 3.2 years CSIPF, 3.6 years Lone-IPF (log rank p value 0.49). Among patients with pulmonary sarcoidosis, mean time from diagnosis to death: 21.4 years. Conclusions Clinical characteristics/behavior of patients with CSIPF was similar to Lone-IPF patients. It is possible that patients with sarcoidosis coincidentally developed IPF and/or have occult genetic predisposition factors to manifest both diseases at different time points. Further study is needed.