Figure 1

Pathways of tumor cells invading the nerves and vessels. Tumor cells are transmitted indirectly via lymphatic or lymphatic vein exchange channels rather than directly via blood vessels. LVI refers to the localization of tumor cells in the vascular lumen or local adhesion to the vascular wall. PNI refers to cells being close to the nerves and involves 33% of tumor cells or the invasion of three layers of the nerve sheath. A black and thickened arrow in the figure indicates the direction of tumor cell invasion. PNI perineural invasion, LVI lymphovascular invasion.