This feature can be observed by histological examination of lung tissue. The feature can be seen in pulmonary veno-occlusive disease (PVOD). PVOD is characterised by diffuse occlusion of the pulmonary veins by fibrous tissue, pulmonary venous congestion and associated complications including severe pulmonary hypertension (pHTN), non-cardiogenic pulmonary oedema, hypoxia and right-ventricular failure. Clinical presentation is typically non-specific, including dyspnoea, fatigue and cough.