Fig. 4

Representative radiological and pathological images of a Cluster 2 case with progressive pulmonary fibrosis. Representative high-resolution computed tomography (HRCT) images of a case in Cluster 2 that developed progressive pulmonary fibrosis (PPF), and pathological images of lung biopsy specimens collected by surgical lung biopsy (SLB) (first biopsy) and transbronchial lung cryobiopsy (TBLC) (second biopsy) were shown. Coronal (A) and axial (B) views at the initial visit, and coronal (C) and axial (D) sections from a 3-year follow-up HRCT taken just before transbronchial lung cryobiopsy (TBLC) are shown. Compared to HRCT images at first visit, progression of reticulation, traction bronchiectasis and ground-glass opacity (GGO) were observed at 3-year follow-up. A haematoxylin–eosin (HE)-stained overview (E), along with magnified HE-stained (F) and Elastica van Gieson (EVG)-stained images (G) of the specimen obtained from SLB, are shown (The scale bars represent 4 mm, 300 μm, and 300 μm, respectively). Similarly, HE-stained overview (H) and HE- (I) and EVG-stained (J) magnified images of the TBLC specimens are shown (The scale bars indicate 4 mm, 300 μm, and 300 μm, respectively). Compared with the SLB specimens which presented diffuse inflammatory cellular infiltration with fibrosis, the TBLC specimens showed a marked increase in fibrosis with collapsed airspace and a significant decrease in inflammatory cellular infiltration.