Collagen deposition (red) from Sirius stain was noticeably present with high density in late-stage IPF compared to the early stage with fibrosis, observed at the perilobular area of the lung.

The Sirius red stain shows 14% collagen proportionate area (B). At the time of the biopsy, HVPG was 11 mm Hg, and the liver stiffness was 16.6 kPa.