Extrahepatic recurrence of HCC is rare compared with intrahepatic recurrence after curative liver resection. The most common sites of extrahepatic recurrence are the lungs, bones, lymph nodes, peritoneum, adrenal glands, and the brain. Lymph node recurrence after curative liver resection is found in only 1.6% of the cases [5]. Although the clinical significance of surgical resection of such lymph node metastases remains controversial, the efficacy of local therapy, including surgical resection of extrahepatic lesions, has been reported. Some studies have reported that complete removal of metastatic lymph nodes is clinically beneficial for patients with HCC with resectable or controllable intrahepatic lesions [6, 7]. In addition, survival rates are expected to improve after resection of solitary lymph node metastases [7]. In the present case, the patient had solitary lymph node metastasis and no other recurrent lesions for > 8 years after the initial operation. Thus, in this case, we considered that a survival benefit could be expected from surgery for lymph node recurrence.

ICG binds to α-lipoproteins, Î2-lipoproteins, albumin, and α2-globulin. Fluorescent imaging using ICG can detect liver cancers through visualization of the disordered biliary excretion of ICG in cancer and noncancerous liver tissues compressed by the tumor. ICG-fluorescence imaging enables highly sensitive identification of tumor location, thereby contributing to accurate liver resection [3]. In contrast, ICG fluorescence has been reported to be more useful in detecting extrahepatic metastasis than in detecting primary HCC and intrahepatic metastasis. ICG remains in tumor cells for a longer time because there is no transbiliary excretion pathway from tumor tissue to non-tumor tissue. In addition, the contrast of ICG fluorescence is enhanced in extrahepatic metastases because of the absence of fluorescence in the background [8]. Previous studies have shown that ICG fluorescence is useful for detecting metastatic lymph nodes in HCC [4, 9, 10]. In fact, Satou et al. revealed that lymph node metastasis could be detected by only faint fluorescence of ICG after dissecting the surrounding tissue, even if it was deeply present in the soft tissue [4]. In agreement with these reports, faint fluorescence of ICG in metastatic lymph nodes was also observed after dissecting the severe adhesions in our case, following accurate identification of the outline of the tumor. Thus, the intraoperative use of ICG has the potential to detect small extrahepatic metastases that cannot be detected on preoperative imaging despite the small number of reports on surgical treatment for metastatic lesions.

The ICG fluorescence pattern depends on the differentiation level of HCC [11]. Well-differentiated HCC shows intense and homogeneous fluorescence, moderately differentiated HCC shows partial fluorescence, and poorly differentiated HCC and liver metastases show a fluorescent halo corresponding to peritumor fluorescence. Thus, ICG is less likely to accumulate in poorly differentiated HCC than in the well-differentiated ones. In previous studies, ICG was injected intravenously at a dose of 0.5 mg/kg body weight, 3 days (1–5 days) before surgery to investigate lymph node metastasis, as well as pulmonary, adrenal, and peritoneal metastasis of HCC. Consequently, these reports showed the potential advantages of ICG for the intraoperative detection of extrahepatic metastasis [4, 12, 13]. In our case, ICG was injected intravenously before surgery at the same dose used for the evaluation of liver function, and the final pathological diagnosis was moderately differentiated HCC. ICG fluorescence, which had a partial accumulation similar to that described in previous reports, was detected in the metastatic lymph nodes. However, the optimal timing and dose of ICG administration remains to be determined [14]. To our knowledge, there have been only three reports of surgical treatment with ICG for lymph node metastasis in HCC [4, 9, 10]. Further studies are required to clarify the relationship between ICG uptake and lymph node metastasis in HCC. This would contribute to the establishment of a surgical treatment strategy for extrahepatic HCC metastasis.