Diagnosis of idiopathic pulmonary fibrosis (IPF) is challenging, and the cooperation between different specialists including pulmonologists, radiologists and pathologists is highly recommended in order to optimize the diagnostic process, avoiding unnecessary and harmful invasive procedures. The recognition of the usual histological pattern of interstitial pneumonia is not easy in some cases, and immunohistochemical markers can be applied to better visualize subtle microenvironmental changes in lung parenchyma. New data regarding the complex pathogenesis of IPF is helping to understand the severe lung remodeling that characterizes this disease, and may also provide new diagnostic criteria.