Figure 3.

Schematic illustration of the four different plexiform lesion types. Type 1: in monopodial branches, often with a connection to the vasa vasorum (in red). Type 2: between pulmonary arteries (orange) and airways (blue) as a tortuous transformation of intrapulmonary bronchopulmonary anastomoses (IBA), connecting the pulmonary artery with peribronchiolar vessels (red). Type 3: at unexpected abrupt ends of distal pulmonary arteries/arterioles. Often, small dilated vessels are seen leaving type 3 lesions (red). Type 4: completely occluded pulmonary arteries with recanalization, or incomplete blockage.