Cytological features of four cases of pulmonary alveolar proteinosis diagnosed by bronchoalveolar lavage fluid cytology

Abstract

Background : Pulmonary alveolar proteinosis (PAP) is a relatively rare disease characterized by abnormal accumulation of a surfactant-derived substance in the alveolar spaces and respiratory bronchioles. Herein, we describe the cytological findings of bronchoalveolar lavage fluid (BALF) obtained from 4 cases of PAP diagnosed by BALF cytology.

Cases : BALF cytology and transbronchial lung biopsy (TBLB) were performed to make a definitive diagnosis in 4 patients aged between 20 and 60 years old suspected as having PAP by computed tomography. The BALF appeared mildly to markedly cloudy : the degree of cloudiness varied among the four cases. Cytology showed granular material, globular amorphous material and foamy macrophages, in varying numbers, in all the cases. The BALF was periodic acid-Schiff positive, and also showed positive immunocytochemical staining for surfactant protein A. On the basis of these findings, we were able to make a definitive diagnosis of PAP. The number of macrophages decreased as the PAP progressed. TBLB also demonstrated the alveolar lesions of PAP : accumulation of eosinophilic materials and foamy macrophages in the alveolar spaces.

Conclusion : The cytological findings in BALF of granular material, globular amorphous material and foamy macrophages is quite useful for the diagnosis of PAP. Moreover, we found that the number of macrophages was correlated with disease progression.