The goal of this observational study is to learn about the diagnostic effectiveness, safety, and influencing factors of transbronchial cryobiopsy（TBLC） in progressive pulmonary fibrosis.

The goal of this observational study is to learn about the diagnostic effectiveness, safety, and influencing factors of transbronchial cryobiopsy（TBLC） in progressive pulmonary fibrosis. The main question it aims to answer are: • The diagnostic rate of MDD1 or MDD2 based on TBLC. • The rate of hemorrhage, pneumothorax, acute ILD exacerbation and mortality. Participants' medical records will be collected by us.

Inclusion Criteria:

Patients with PPF, ≥18 years of age, unclassified ILD, HRCT ≤3 months, forced vital capacity (FVC)≥50% predicted value, pulmonary carbon monoxide diffusion (DLCO)≥35% predicted value, echocardiography ≤12 months, estimated pulmonary systolic blood pressure ≤40 mmHg, Body mass index (BMI)≤35 kg/m2.

Exclusion Criteria:

Patients with platelet counts below 50,000e+9/L or International Normalized ratio of prothrombin time (INR) above 1.5 are not eligible for TBLC

Patients receiving TBLC for progressive pulmonary fibrosis