Clinicopathological Evolution of Pyrrolizidine Alkaloid-induced Liver Injury: Transition From SOS to PSVD?

BACKGROUND AND AIMS: Hepatic sinusoidal obstruction syndrome (SOS) is characterized by hepatic sinusoidal endothelial cell injury and detachment, hepatic sinusoidal congestion, and hepatic cell necrosis. Currently, limited data exist concerning changes during the recovery period, especially histopathological changes. The purpose of this study was to investigate the evolution of pathology in patients with pyrrolizidine alkaloid (PA)-induced SOS and in a monocrotaline-induced SOS rat model.

METHODS

Patients diagnosed with PA-induced SOS who underwent liver biopsy after achieving clinical remission were consecutively enrolled in this retrospective study. To compare the clinical and pathological differences between patients with acute and convalescent SOS, a 2:1 matched analysis was performed based on age, sex, treatment regimen, and baseline Drum Tower Severity Scoring (DTSS) during the acute phase. Additionally, an animal model of PA-induced SOS was established through the administration of monocrotaline.

RESULTS

Fourteen consecutive patients with SOS who had adequate liver biopsy specimens obtained during recovery were identified. During convalescence, most laboratory and imaging findings, such as the map-like enhancement observed on computed tomography, also disappeared. However, histopathological analysis revealed a distinct shift from hepatic sinusoidal endothelial cell injury in the acute phase to portal tract abnormalities, primarily characterized by portal vein stricture, in the recovery phase. These pathological changes were corroborated in our animal model.

CONCLUSIONS

Our study suggests that both patients with PA-induced SOS and rats in the convalescent stage may exhibit porto-sinusoidal vascular disease-like changes. Regular follow-up and dynamic pathological assessment are therefore recommended to facilitate the early detection of potential signs of portal hypertension.