Table 3.

Grading system proposed by Lu et al. [17] for predicting vascular invasion by tumor based on the degree of tumor contiguity with a vessel

Category	Description	Comment
Grade 0	No contiguity of tumor with a vessel	Vascular invasion in 0% of cases
Grade 1	Tumor contiguous with <25% of the circumference of a vessel	Vascular invasion in 0% of cases
Grade 2	Tumor contiguous with 25–50% of the circumference of a vessel	Vascular invasion in 57% of cases
Grade 3	Tumor contiguous with 50–75% of the circumference of a vessel	Vascular invasion in 88% of cases
Grade 4	Tumor contiguous with >75% of the circumference of a vessel or any vessel constriction	Vascular invasion in all cases