Idiopathic Pulmonary Fibrosis
- Diffuse interstitial pulmonary fibrosis occurs secondary to a variety of pulmonary diseases, especially in their end-stage. However, Idiopathic Pulmonary Fibrosis (IPF) is reserved for cases where the morphological finding of diffuse interstitial pulmonary fibrosis occurs in the absence of other known causes. As indicated by its name, the pathogenesis of IPF is poorly-understood but may represent a the chronic activation of healing-processes in response to repeated bouts of inflammation caused by a cryptic injury.
- The morphological manifestation of IPF is termed "Usual Interstitial Pneumonia (UIP)". The hallmark of UIP is its patchy distribution which will include interspersed areas of inflammation, fibrosis, and normal lung. Areas of inflammation typically involve infiltration of plasma cells and lymphocytes in the alveolar septa along with proliferation of type II pneumocytes. The diffuse but patchy interstitial fibrosis of UIP is typically progressive and can develop into a honeycomb lung picture at its end-stage.
- IPF manifests with the insidious onset of exertional dyspnea and a non-productive cough that can acutely worsen to include hypoxemia. Pulmonary function tests typically reveal of restrictive pattern of pulmonary function along with reduced pulmonary diffusing capacity, indicating the presence of diffusion defects.