Table 1.
PNM classification of alveolar echinococcosis (according to WHO-IWGE, 2006).
| PNM | Location and extension of the lesion |
|---|---|
| P | Hepatic localization of the parasite |
| P X | Primary parasite cannot be assessed |
| P 0 | No detectable parasite 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 with extension along the vesselsb and the biliary tree |
| N | Extrahepatic involvement of neighboring 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 | The absence or presence of distant Metastasis [lungs, distant lymph nodes, spleen, CNS, orbital, bones, skin, muscle, kidneys, distant peritoneum, and retroperitoneum] |
| M X | Not completely evaluated |
| M 0 | No metastasisc |
| M 1 | Metastasis |
a
For classification, the plane projecting between the bed of the gall bladder and the inferior vena cava divides the liver into two lobes.
b
Vessels mean inferior vena cava, portal vein, and arteries.
c
Chest X-ray and cerebral CT negative.