Diagnosis of idiopathic pulmonary fibrosis (IPF): histologic and HRCT diagnosis

Abstract

Neither the pathologist nor the radiologist makes the diagnosis of IPF. It is a clinical diagnosis. Current recommendations are that the diagnosis of IPF follows multidisciplinary discussion (MDD) involving clinicians, radiologists and, if tissue is take, pathologists. According to the 2011 IPF guidelines, the diagnosis of IPF requires the pathologic and/or radiologic pattern of usual interstitial pneumonia (UIP) on surgical lung biopsy or HRCT respectively. IPF represents UIP of unknown cause. UIP ≠ IPF. There are other causes of UIP including chronic hypersensitivity pneumonitis, connective tissue diseases, familial pulmonary fibrosis, some drug reactions and miscellaneous rare conditions. Clues to these other causes of UIP can be histologic, radiologic, serologic, or clinical. Chronic hypersensitivity pneumonitis may have giant cells, granulomas, and central lobular pathologic changes. Connective tissue diseases may have clues in the serology, clinical history, or prominent inflammatory infiltrate and/or numerous germinal centers histologically. Clues to familial fibrosis and drug reactions are often historical. The radiologic features of UIP on HRCT can be summarized as peripheral basal honeycombing with little or no ground glass change; some recent studies suggest that there may be some modification to these criteria and honeycombing may not always be required. Neither the pathologist nor the radiologist makes the diagnosis of IPF. It is a clinical diagnosis. Current recommendations are that the diagnosis of IPF follows multidisciplinary discussion (MDD) involving clinicians, radiologists and, if tissue is take, pathologists. According to the 2011 IPF guidelines, the diagnosis of IPF requires the pathologic and/or radiologic pattern of usual interstitial pneumonia (UIP) on surgical lung biopsy or HRCT respectively. IPF represents UIP of unknown cause. UIP ≠ IPF. There are other causes of UIP including chronic hypersensitivity pneumonitis, connective tissue diseases, familial pulmonary fibrosis, some drug reactions and miscellaneous rare conditions. Clues to these other causes of UIP can be histologic, radiologic, serologic, or clinical. Chronic hypersensitivity pneumonitis may have giant cells, granulomas, and central lobular pathologic changes. Connective tissue diseases may have clues in the serology, clinical history, or prominent inflammatory infiltrate and/or numerous germinal centers histologically. Clues to familial fibrosis and drug reactions are often historical. The radiologic features of UIP on HRCT can be summarized as peripheral basal honeycombing with little or no ground glass change; some recent studies suggest that there may be some modification to these criteria and honeycombing may not always be required.