Cellosaurus Disease Terminology Pulmonary Fibrosis Idiopathic Pulmonary Fibrosis Idiopathic Pulmonary Fibrosis Chronic and progressive fibrosis of the lung parenchyma of unknown cause. C1800706 Idiopathic_Pulmonary_Fibrosis Cellosaurus C35716 IPF A disease in which the alveoli (tiny air sacs at the end of the bronchioles in the lungs) are overgrown with fibrous tissue. The cause of the disease is unknown and it gets worse over time. Symptoms include difficult, painful breathing and shortness of breath. Idiopathic Pulmonary Fibrosis Disease or Syndrome idiopathic pulmonary fibrosis