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

For classification, the plane projecting between the bed of the gall bladder and the inferior vena cava divides the liver into two lobes.


Vessels mean inferior vena cava, portal vein, and arteries.


Chest X-ray and cerebral CT negative.

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