The Application of Transbronchial Cryo-biopsy in the Diagnosis of Pulmonary Alveolar Proteinosis.

Background: Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by abnormal alveolar surfactant accumulation. In recent years, transbronchial cryo-biopsy (TBCB) has gradually been applied as it can obtain larger and better-quality specimens. This study aims to assess the diagnostic yield and safety of TBCB in PAP.

Methods: This study included 78 PAP patients who underwent lung biopsy. Thirty-six of them underwent transbronchial lung biopsy (TBLB) with forceps and the other 42 underwent TBCB. Clinical data, biopsy specimen number and size, the pathologic lesion proportion of biopsied specimens, complications, and pathologic diagnosis of patients from both groups were recorded.

Results: Our data show that the diagnostic yield of TBCB is significantly superior to that of TBLB (78.6% vs. 50%, P<0.05). The TBCB group exhibited a greater number and size of biopsy specimens than the TBLB group (P<0.05). As for pathologic diagnosis, the specimen size in the PAP-positive group was notably larger than in the PAP-negative group (P<0.05). According to the receiver operating characteristic curve, the specimen size of at least 2 mm2 was identified as the cut-off with a higher positive predictive value (area under the curve = 0.676, P=0.007). For complications of TBLB and TBCB, there was no statistically significant difference in the incidence of pneumothorax and bleeding.

Conclusions: TBCB emerges as a minimally invasive, effective, and safe technique with a higher diagnostic yield than TBLB in PAP. Augmenting the specimen size can effectively improve the diagnostic yield.