EXTRAHEPATIC BILE DUCTS – PERIHILAR (ICD‐O‐3 C24.0)

Rules for Classification

The classification applies to carcinomas of the extrahepatic bile ducts of perihilar localization (Klatskin tumour). Included are the right, left and common hepatic ducts.

Anatomical Sites and Subsites (Fig. 221)

Perihilar cholangiocarcinomas are tumours located in the extrahepatic biliary tree proximal to the origin of the cystic duct.

Schematic illustration of Anatomical Sites and Subsites. — **Fig. 221**

Regional Lymph Nodes

The regional nodes are the hilar and pericholedochal nodes in the hepatoduodenal ligament.

TNM Clinical Classification

T – Primary Tumour

TX	Primary tumour cannot be assessed
T0	No evidence of primary tumour
Tis	Carcinoma in situ
T1	Tumour confined to the bile duct, with extension up to the muscle layer or fibrous tissue (Fig. 222)
T2a	Tumour invades beyond the wall of the bile duct to surrounding adipose tissue (Fig. 223)
T2b	Tumour invades adjacent hepatic parenchyma (Fig. 224)
T3	Tumour invades unilateral branches of the portal vein or hepatic artery (Fig. 225a)
T4	Tumour invades the main portal vein or its branches bilaterally; or the common hepatic artery; or the second‐order biliary radicals bilaterally; or unilateral second‐order biliary radicals with contralateral portal vein or hepatic artery involvement (Fig. 225b)

Schematic illustration of tumour confined to the bile duct, with extension up to the muscle layer or fibrous tissue. — **Fig. 222**

Schematic illustration of tumour invades beyond the wall of the bile duct to surrounding adipose tissue. — **Fig. 223**

Schematic illustration of tumour invades adjacent hepatic parenchyma. — **Fig. 224**

Schematic illustration of tumour invades unilateral branches of the portal vein or hepatic artery. — **Fig. 225**

N – Regional Lymph Nodes

NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastases to 1 to 3 regional lymph nodes
N2	Metastases to 4 or more regional nodes

M – Distant Metastasis

M0	No distant metastasis
M1	Distant metastasis

TNM Pathological Classification

The pT and pN categories correspond to the T and N categories.

pM1	Distant metastasis microscopically confirmed

Note

pM0 and pMX are not valid categories.

pN0

Histological examination of a regional lymphadenectomy specimen will ordinarily include 15 or more lymph nodes. If the regional lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0.