Figure 2.

Pathologic schema of UIP. In the early phase, patchy dense fibrosis involves peripheral and perivenular areas, but the architectural destruction is mild. Here, a fibroblastic focus is located between the fibrotic area and normal lung. In the later phase, structural remodeling due to wider fibrosis causes shrinkage, where that honeycomb cysts develop in association with traction bronchiolectasia. Red lines: arteries; blue lines: veins; yellow lines: lymphatic ducts; and green areas: FF.