LAUSR

BACKGROUND No authors have reported occult liver metastases from perihilar cholangiocarcinoma (PHCC), which are defined as intrahepatic metastases that are overlooked by preoperative workup and intraoperative inspection but are detected by final pathology. The aim of this study was to clarify the features of such unappreciated metastases. METHODS We reviewed retrospectively the medical records of patients with PHCC treated between 2001 and 2016 with attention to liver metastases. RESULTS During the study interval, 945 consecutive patients with PHCC were treated, including 260 unresected and 685 resected patients (672 with hepatectomy and 13 without). Of these, 36 patients had overt liver metastases. Of the 672 hepatectomized patients, 21 (3.1%) patients had occult liver metastases with a median number of 1 (range 1-6). When compared between occult and overt metastases, the diameter was smaller in the former (5 mm vs 12 mm, P < .001). When compared between the 21 patients with occult metastases and the 645 hepatectomized patients without liver metastases, microscopic venous invasion and lymph node metastases were observed frequently in the patients with occult metastases. Survival for these 21 patients with occult metastases was better than that for the 36 patients with overt metastases (median survival time; 17.1 vs 7.4 months, P < .01). CONCLUSION Occult liver metastases from PHCC are not extremely rare. Meticulous handling of the resected specimens is crucial to detect such metastases. Although patients with occult metastases had advanced stages of the disease, their survival was better than that for patients with overt metastases.