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Page 2 of 6 Ohtsuka et al. Hepatoma Res 2024;10:18 https://dx.doi.org/10.20517/2394-5079.2024.04

INTRODUCTION
Since lymphatic drainage from the liver has been reported to adhere to segmental anatomy, regional lymph
nodes (LNs) of intrahepatic cholangiocarcinoma (ICC) are indicated to be different between the tumors in
the right-sided and left-sided liver . However, the pathway of the lymph vessels (LVs) to regional LNs
[1,2]
from ICC, especially in the left-sided liver, has not been clearly described, although this is essential when
considering LND performed to improve patient survival.

LYMPHATIC SYSTEM IN THE LIVER
The hepatic lymph originates from the space of Disse . It then enters three lymphatic pathways: portal,
[3]
[3,4]
sublobular (hepatic venous), and subcapsular . The portal and sublobular lymphatic pathways constitute
the deep lymphatic system, while the subcapsular lymphatic pathway is called the superficial lymphatic
system . The subcapsular LVs lie beneath the hepatic capsule and collect lymph in the interstitial space of
[3-5]
[4]
the capsule that flows from the sinusoids located close to the capsule . The sublobular LVs travel around
the central vein, sublobular vein, and hepatic vein to the LVs around the vena cava . The subcapsular and
[3,4]
sublobular lymphatic pathways, however, are minor systems of lymphatic drainage, with 20% or less of
hepatic lymph draining through these pathways. The majority (80% or more) of hepatic lymph drains
through the portal lymphatic pathway. The portal LVs are located along with the portal tracts, and lymph
fluid flows in the same direction as the bile .
[3,4]

Lymphatic drainage from the left-sided liver continues from the superficial and deep lymphatic systems in
the liver . In the superficial lymphatic system, lymph from the anterior surface of the liver flows through
[5]
the coronary, triangular, and falciform ligaments to LNs in the thoracic region across the diaphragm, while
lymph through the fibrous appendix of the liver directly reaches the paraaortic LNs. Lymph from the
posterior surface flows toward the inferior phrenic nodes, and from the inferior surface toward the hepatic
hilum and also the gastrohepatic ligament, where it joins the LVs located there. In the deep lymphatic
system, LVs around the middle and left hepatic vein and the vena cava connect with the LNs in the
posterior mediastinum. The efferent portal LVs from the left-sided liver, which are the most important
lymphatic drainage pathway, communicate with the LVs and LNs along the hepatic artery at the
hepatoduodenal ligament and further along the common hepatic artery (CHA) toward the celiac artery
[5,6]
(CEA) . In addition to this pathway, lymph in the portal LVs is believed to flow also through the lesser
omentum to the perigastric and paracardial LNs, and then to the left gastric LNs , although the exact path
[5-8]
in the lesser omentum to the left gastric LNs has been inconsistent among previous literature.

CONTROVERSY OF LYMPHATIC PATH TOWARD LEFT GASTRIC LYMPH NODES FROM
LEFT-SIDED ICC
[1]
The eighth edition of the American Joint Committee on Cancer (AJCC) staging manual only showed that
tumors in the left-sided liver may preferentially drain to LNs along the lesser curvature of the stomach.
Tsuji et al. showed a pathway to the left gastric LNs through the pericardial and perigastric along the lesser
curvature . Similarly, Okami et al. described a pathway that passes through the lesser omentum to the
[7]
cardiac portion of the stomach and the gastric lesser curvature, independent of the pathway through the
[6]
hepatoduodenal ligament . Cho et al. also illustrated a similar pathway . On the other hand, Morine et al.
[8]
explained a pathway to gastrocardiac LNs via hilar LNs .
[5]
ACTUAL LYMPHATIC SPREAD FROM LEFT-SIDED ICC
From September 2002 to August 2019, 48 patients with left-sided ICC underwent surgical treatment at the
Chiba University Hospital. Of these, 23 (48%) had LNM, of which 11 (48%) had LNM associated with the