The diagnostic value of bronchoalveolar lavage and transbronchial lung biopsy in cryptogenic organizing pneumonia

In order to determine the diagnostic value of bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB) in cryptogenic organizing pneumonia (COP) a prospective study was carried out. Thirty seven consecutive patients (20 males and 17 females) with clinicoradiological features of COP were enrolled in the study. The statistical analyses were completed in 35 cases. Twenty eight patients were diagnosed to have COP, all of them with a confirmatory biopsy. In seven cases, a different diagnosis was made. BAL cytological and phenotypical criteria considered for the diagnosis of COP were: a lymphocytosis of more than 25% (with a CD4/CD8 ratio less than 0.9); combined with at least two of the following data (foamy macrophages of > 20%, and/or neutrophils of > 5%, and/or eosinophils of > 2% and < 25%). TBLB specimens were classified as positive for COP if they showed: buds of granulation tissue within the centrilobular air spaces; infiltration of alveolar walls with chronic inflammatory cells; and preservation of alveolar architecture. BAL was performed in 34 patients; 17 cases were consistent with the final diagnosis of COP (sensitivity 63%), and four cases were correctly classified as negative (specificity 57%). BAL had a positive predictive value (PPV) of 85% and a negative predictive value (NPV) of 29%. TBLB was performed in 32 patients; it correctly identified COP in 16 cases (sensitivity 64%), and six cases were correctly classified as negative (specificity 86%). TBLB had a PPV of 94% and a NPV of 40%. The accuracy of the examinations, that is the probability of correctly diagnosing both diseased and nondiseased patients by BAL or TBLB, was 62 and 69%, respectively. Our findings suggest that the combination of cytological bronchoalveolar lavage and histological transbronchial lung biopsy data obtained during a fibreoptic procedure appears to be an effective method for the initial investigation in cryptogenic organizing patients pneumonia presenting with patchy radiographic shadows.