Use of Riu stain in the immediate interpretation of bronchial brushing cytology. Comparison with Papanicolaou stain and histology

Abstract

Objective: To determine the usefulness of Riu stain in the immediate interpretation of cytologic material from bronchoscopic brushings and its accuracy in the diagnosis of lung malignancies.

Study design: A prospectively comparative study between Riu and Papanicolaou stain with pathologic control was conducted. Eighty-six patients with central lung lesions, visible during fiberoptic bronchoscopy, were studied. Endobronchial biopsies and brushings were performed at the time of the same procedure.

Results: The diagnostic accuracy of Riu stain for malignancy was 97%, with a sensitivity of 99%, specificity of 85%, positive predictive value of 97% and negative predictive value of 92%. As for the Papanicolaou technique, the diagnostic accuracy for malignancy was 97%, with a sensitivity of 97%, specificity of 92%, positive predictive value of 99% and negative predictive value of 86%. The overall cytologic typing accuracy of Riu stain was 86%, which was comparable with that of Papanicolaou stain (90%, P = .48). Both techniques are more accurate in the diagnosis of squamous carcinoma, small cell carcinoma and adenocarcinoma than in large cell carcinoma.

Conclusion: Riu stain is rapid, simple to use and, most important, accurate for the identification of lung malignancies. It can increase the diagnostic success rate, prevent unnecessary repeat bronchoscopies and lower related complications.