Transmission Electron Microscopy of Sputum Deposition in the Diagnosis of Pulmonary Alveolar Proteinosis

Abstract

Objective: To clarify the diagnostic value of sputum in pulmonary alveolar proteinosis (PAP) through transmission electron microscopy (TEM) of sputum deposition (SD).

Methods: Eleven SD samples and 9 bronchoalveolar lavage (BAL) sediments from a PAP group including 11 patients were observed by TEM and compared with sputum direct smear, BAL cytology, and lung biopsy histopathology. Eleven healthy adults were chosen as controls.

Results: The 11 sputum smears from the PAP group showed no diagnostic component, but TEM of SD revealed 7 of 11 samples had many myelin-like lamellar bodies with degeneration in the cytoplasm of macrophages, alveolar epithelial cells, and extracellular spaces, which suggested PAP. Especially, 2 patients on whom lung biopsy could not be performed and who failed to be diagnosed by BAL fluid were finally diagnosed by TEM of SD. TEM of BAL sediments showed 7 of 9 cases had diagnostic myelin-like lamellar bodies. No statistical significance was found between BAL fluid and SD by TEM. The control group didn’t show diagnostic components by cytology or TEM of SD.

Conclusion: TEM of SD is an important noninvasive diagnostic method especially for patients against lung biopsy and BAL.

Keywords::

• Bronchoalveolar lavage fluid
• diagnosis
• electron microscopy
• pulmonary alveolar proteinosis
• sputum
• ultrastructure

ACKNOWLEDGEMENT

The authors thank Meifang Zhu, Jianping Fang, Yudong Zhang, Jun Gu, Weizhe Qiu, and Zhangjun Zheng for their skillful technical assistance. This work was funded by Science and Technology Commission of Shanghai Research Fund Project (034119868) and Shanghai Science and Technology Commission Foundation of key medical research (09411951600).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.