Interstitial lung disease. Part I. A multidisciplinary approach to the diagnosis and assessment of disease activity.

The value of alveolar lavage as an investigative technique was determined in patients with interstitial lung disease. Alveolar cytology was related to defined histopathological degrees of disease activity found in transbronchial biopsy specimens. The degree of disease activity as assessed by these two techniques was compared with radiological evaluation. Adequate specimens of lung tissue for histopathological evaluation were obtained by transbronchial biopsy in 95% of the subjects during the first procedure and diagnostic histopathological changes were found in 60% of the patients. In the evaluation of disease activity, the lymphocyte-macrophage (L-M) ratio and, to a lesser extent, the total alveolar cell counts correlated well with graded histopathological changes of activity. A graded radiological evaluation of activity was accurate in 14 out of 17 patients, but in 3, extreme cellular disease ws not recognized. Alveolar cytological examination can be employed as a supplement to the biopsy technique for increased accuracy in the initial and follow-up evaluation of active interstitial lung disease. An approach combining transbronchial biopsy, alveolar lavage and radiography, provides a safe and accurate alternative to openlung biopsy in most patients for determining the aetiology and degree of activity of interstitial lung disease.