Induced sputum deposition improves diagnostic yields of pulmonary alveolar proteinosis: A clinicopathological and methodological study of 17 cases

ABSTRACT

Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease characterized by the accumulation of intra-alveolar lipoprotein-like surfactants. Lung core biopsy and bronchoalveolar lavage (BAL) fluid are currently the two major sources of sampling for diagnosis. In the present study, we assessed the value of induced sputum in diagnosing PAP by transmission electron microscopy and examined the PAP 2-year death rate in Asians. Transmission electron microscopy was performed on the samples from 17 patients with PAP, 13 patients with inflammatory lung diseases, and 13 healthy adults. The PAP patients were followed up for 3–156 months, and inflammatory lung diseases patients or healthy adults for 12–36 months. The ultrastructural features including diagnostic lamellar bodies of induced sputum deposition (ISD) samples were similar to that of the BAL fluid sediment. However, the rates of lamellar bodies were 73.7% in the ISD group, significantly higher than the spontaneous sputum deposition (SSD) group (42.1%, P < .0487) and similar to the BAL sediment (76.2%) and the lung biopsy (54.5%) groups. The overall 2-year death rate of our PAP patients was 17.6% (3/17), not statistically different from the healthy adults and patients with inflammatory diseases (0/13, P = .237 for both). ISD may be the preferred non-invasive sampling method for diagnosing PAP by electronic microscopy because of the higher diagnostic yield than SSD. The diagnostic yields of this noninvasive method were similar to that of lung core biopsy and BAL.

KEYWORDS:

• Bronchoalveolar lavage fluid
• electron microscopy
• induced sputum
• pathology
• pulmonary alveolar proteinosis
• sputum

Additional information

Funding

This study was supported by grants from the Shanghai Science and Technology Committee of Medical Key Technology Research Fund (09411951600), the Medical Key Special Fund from the Shanghai Municipal Health Medical Bureau (20134034), the Medical Science and Technology Development Research Center Fund of the Ministry of Health (W2013GJ61), and the National Natural Science Foundation of China (81570053).