A noninvasive examination for the diagnosis of pulmonary alveolar proteinosis: induced sputum in conjunction with transmission electron microscopy.

Transmission electron microscopy (TEM) of sputum deposition (SD) is an important method to assist in the diagnosis of pulmonary alveolar proteinosis (PAP). However, the low positive rate and poor quality of slices restrict the application of sputum samples in the diagnosis of PAP. Furthermore, it can be more difficult to obtain a sufficient amount of sample for TEM if the patients have little or no sputum. In this paper, we successfully diagnosed a patient with PAP using induced sputum deposition (ISD) with TEM, which is a novel and noninvasive method for PAP diagnosis. Therefore, ISD combined with TEM can be an effective method for PAP diagnosis, especially when a lung biopsy and bronchoalveolar lavage (BAL) cannot be performed, or little or no sputum can be obtained.