Veno-occlusive disease of the lung after allogeneic haematopoietic stem-cell transplantation: An autopsy study

Pulmonary veno-occlusive disease (pVOD) is a potentially life-threatening sequela of allogeneic haematopoietic stem-cell transplantation (alloHSCT). We conducted a morphometric evaluation of autopsy lung tissue to determine the incidence of pVOD and its association with donor type, conditioning regime, hepatic sinusoidal obstruction syndrome (hSOS), survival time, and graft versus host disease (GvHD). The degree of occlusion of pulmonary veins in 78 autopsy cases after alloHSCT and 12 control cases was assigned to one of the following categories: none, minor thickening of the intima (up to 33% narrowing), moderate pVOD wherein about half of the lumen (34–66%) is occluded, or advanced pVOD with near total or total (67–100%) obliteration of the lumen. Minor thickening of the intima was found in all patients after alloHSCT (median: 66% of the vessels) and it was found to a lesser extent in the control cases (median: 12%). Moderate to advanced pVOD was seen in 95% of the cases, but only in a minority of the veins and venules (median: 6% of the veins and venules). PVOD was not significantly correlated with other histopathological findings within the lungs, including acute pneumonia, desquamative pneumonia, acute respiratory distress syndrome, organising and non-specific pneumonia, and bronchiolitis obliterans or acute lung disease. PVOD was significantly associated with a conditioning regimen including cyclophosphamide, fludarabine, or antithymocyte globulin and the duration of survival after alloHSCT. It was not associated with acute or chronic GvHD, other intestinal lung diseases, hSOS, or donor characteristics. PVOD was found in most patients after they underwent alloHSCT, although it mainly involved only a minority of the vessels. It was associated with the conditioning regime and the duration of survival after alloHSCT.