Table 1

Pathological characteristics of vasculopathies in pulmonary hypertension

Definition according to Dana point criteriaPresence in Fra-2 tg miceChanges characteristic for human SSc-PAH 6 7Changes characteristic for human IPAH 6 7
Concentric laminar intimal thickeningExpansion of (myo-) fibroblasts, SMCs+++ (figure 1E)+++(+)
Concentric and eccentric non-laminar thickeningPredominantly composed of fibroblasts/connective tissue+ (figure 1F,G)++
Adventitial thickening++ (figure 1F)++++
Medial hypertrophyIncrease due to hypertrophy/-plasia of SMCs, to an increase in connective tissue and elastic fibres, extension of SMCs into non-muscularised arteries+ (figure 1H)++
Plexiform lesionFocal proliferation of endothelial channels lined by myofibroblasts, SMCs and connective tissue matrix(+)+++
Dilation lesionThin-walled vein-like vessel distally to a plexiform lesion+
ArteritisRarely primary, often associated with plexiform/dilation lesions, arterial wall may be necrotic and/or be infiltrated with chronic and acute inflammatory cells+
Perivascular inflammatory infiltrates++ (figure 1H)+++
Interstitial changesFibrosis, inflammatory infiltrates+++ (Supplementary figure 1B–D)+++(+)
Pulmonary occlusive venopathyExtensive and diffuse occlusion of pulmonary venules and veins, occluding fibrous tissue may be loose and edematous with variable cellularity or dense, sclerotic and accellular; intimal thickening mainly involves venules and small veins, luminal occlusion can be solid or eccentric with multiple lumina; media may become thickened with an increase in elastic fibres and SMCs++(+)
Pulmonary microvasculopathyLocalised capillary proliferation that invades pulmonary interstitium, vessels and, less commonly, airways; panlobular and patchy distribution, often associated with pulmonary hemosiderosis
  • −absent.

  • (+)hardly ever present/not characteristic.

  • +rarely/can be observed.

  • ++often/common feature.

  • +++very often/characteristic feature.

  • Fra-2, fos-related antigen 2; IPAH, idiopathic pulmonary arterial hypertension; PAH, pulmonary arterial hypertension; SMC, smooth muscle cells; SSc, systemic sclerosis; tg, transgenic.