Table 1 Histologic grading of sinusoidal obstruction syndrome

Sinusoidal Injury (SI)

 0 - No sinusoidal dilatation or congestion

 1 - patchy/confluent areas of sinusoidal dilatation/congestion without hepatocyte atrophy

 2 - patchy/confluent areas of sinusoidal dilatation/congestion with associated mild hepatocyte atrophy

 3 - patchy/confluent areas of sinusoidal dilatation/congestion with associated moderate or severe hepatocyte atrophy

Nodular Regenerative Hyperplasia (NRH)

 0 - absent

 1 - present

Venous Obstruction (VO)

 0 - absent

 1 - present, partial obstruction of central venule(s)

 2 - present, total occlusion of central venule(s)