Table 2.
PNM classification of alveolar echinococcosis.
| WTO PNM classification P0–4 N0–1 M0–1 | |
|---|---|
| P | Hepatic localization of the parasite |
| P X | Primary tumour cannot be assessed |
| P 0 | No detectable tumour in the liver |
| P 1 | Peripheral lesions without proximal vascular and/or biliary involvement |
| P 2 | Central lesions with proximal vascular and/or biliary involvement of one lobea |
| P 3 | Central lesions with hilar vascular or biliary involvement of both lobes and/or with involvement of two hepatic veins |
| P 4 | Any liver lesion extending along the vesselsb and the biliary tree |
| N | Extrahepatic involvement of neighbouring organs [diaphragm, lungs, pleura, pericardium, heart, gastric and duodenal wall, adrenal glands, peritoneum, retroperitoneum, parietal wall (muscles, skin, bone), pancreas, regional lymph nodes, liver ligaments, kidneys] |
| N X | Not evaluable |
| N 0 | No regional involvement |
| N 1 | Regional involvement of contiguous organs or tissues |
| M | Absence or presence of distant metastasis [lungs, distant lymph nodes, spleen, CNS, orbitals, bone, skin, muscles, kidneys, distant peritoneum and retroperitoneum] |
| M X | Not completely evaluated |
| M 0 | No metastasisc |
| M 1 | Metastasis |
aFor classification, the plane projecting between the bed of the gall bladder and the inferior vena cava divides the liver into two lobes. bVessels refers to the inferior vena cava, portal vein and arteries. cNegative chest X-ray and cerebral CT.