Esophageal cancer is an important cause of cancer death, with an incidence of about 8-10/100 000 and 13 300 deaths in the
2004 . About 35% of all patients already suffer from liver metastasis by the
time of diagnosis of the primary tumor. Since patients are excluded from potentially
curative resection of the tumor when metastases are present, the diagnosis of
liver metastases plays a crucial role for further treatment. The prognosis of
these patients is also highly dependant on the respectability of the tumor. United States
Distant metastases, especially liver metastasis, can be diagnosed by CT scan or MRI with high sensitivity and speciﬁcity. Sensitivities of these diagnostic means range between 74% and 85%. In these series, almost all false-negative results occurred when lesions were less than 1.5 cm in diameter. Therefore, non-invasive detection of small metastases can be difﬁ cult or even impossible. When suspicious lesions are found by CT scan, further differentiation is possible by additional MRI imaging . Differential diagnosis of liver metastases includes benign liver lesions, including hemangiomas, adenomas, von Meyenburg complexes or infectious lesions e.g. miliary tuberculosis .
Bile duct hamartomas (von Meyenburg complexes) of the liver are usually detected during laparotomy or autopsy as an incidental ﬁnding. Multilocular occurrence is possible although they are rarely spread throughout the whole liver, as it was observed in our ﬁrst patient. They may be found in normal liver tissue, but also in association with Caroli’s syndrome, congenital hepatic ﬁbrosis (CHF) or autosomal dominant polycystic kindney disease (ADPKD) . Histology of von Meyenburg complexes consists of a variable number of dilated small bile ducts, embedded in a ﬁbrous, sometimes hyalinizing stroma (Figure 3).
If detected by CT scan or MRI, von Meyenburg complexes appear as small intrahepatic cystoid lesions. The lesions are frequently located adjacent to the portal veins, although the lesions can also be located everywhere else . However, it remains difficult to differentiate between metastases and benign liver lesions. Moreover, small liver lesions with a diameter of less than 1.5 cm are often not detected by CT or MRI .
Since the treatment of metastatic disease is completely different from resectable esophageal cancer, liver lesions need to be identiﬁed and characterized as early as possible.
In our presented patients, the preoperative staging did not reveal any liver metastases. This underlines the importance of exact diagnostic measures in cases of unexpected intraoperative ﬁndings. Besides intraoperative ultrasound of the liver, frozen section is the gold standard for further differentiation of liver lesions of unknown origin.
Von Meyenburg complexes are defined as innocuous lesions. However, there are about 10 reported cases of neoplastic transformation of von Meyenburg complexes resulting in cholangiocarcinomas [2,3].
In conclusion, von Meyenburg complexes are an important differential diagnosis of hepatic metastases. As the existence of liver metastases is crucial for therapeutic decision making in malignant diseases, this differential diagnosis must be carefully clariﬁed. Since von Meyenburg complexes are usually less than 5 mm in size, they can escape preoperative radiologic diagnostics. The macroscopic appearance of von Meyenburg complexes can mimic liver metastasis as demonstrated in our reported patients. This underlines the importance of intraoperative frozen sections to make the correct diagnosis.