The justification for the progressive fibrotic phenotype

Purpose of review Describe the concept and recent data for the concept of progressive fibrotic interstitial lung disease (ILD). Recent findings Making an accurate diagnosis is critical to help determine appropriate therapy and predict prognosis. This is certainly true in the field of ILD where a diagnosis of idiopathic pulmonary fibrosis (IPF) leads a clinician to consider initiation of antifibrotic therapy, and avoidance of immunosuppression due to possible harm, at the time of diagnosis due to the high probability of disease progression. In other types of ILD immunosuppression may be helpful such as those associated with a connective tissue disease or in combination with antigen avoidance in hypersensitivity pneumonia. It is also recognized that despite initial approaches to therapy some non-IPF ILDs will develop progressive fibrosis leading to increased symptoms, decreased quality of life and early mortality. Once fibrosis is present, the biologic pathways responsible for progression can be redundant and respond in a similar fashion to antifibrotic therapy independent of the underlying disease. Summary There are clinical and biological rationale for the justification of a progressive fibrotic phenotype that complements the therapeutic decisions and prognosis provided by initial diagnosis.