Table 1.

PNM classification of hepatic alveolar echinococcosis

Primary hepatic lesion (P)
PX	Primary lesion cannot be assessed
P0	No detectable hepatic lesion
P1	Peripheral hepatic lesion with no proximal hepatic vascular or biliary involvement
P2	Central hepatic lesion with proximal involvement of vessels or biliary ducts in one lobe
P3	Central hepatic lesion with involvement of hilar vessels or biliary ducts in both lobes or with involve-ment of two hepatic veins
P4	Hepatic lesion with extension along the vessels (hepatic veins, portal vein, IVC and hepatic artery) and biliary tree
Neighboring organ involvement (N) including adrenal gland, diaphragm, peritoneum, mesentery, duodenum, stomach, spleen, pancreas, lymph nodes, parietal wall etc.
NX	Cannot be assessed
N0	No surrounding organ involvement
N1	Involvement of surrounding contiguous organs
Absence or presence of metastatic (M) (distant) organ involvement
MX	Distant organs not evaluated
M0	No metastases
M1	Metastases