[Liver metastases of unknown origin.]

Approximately 5% of cancer patients are diagnosed with tumour of unknown origin (3-4% in Iceland). Of those 10-30% have liver metastases. Liver metastases of unknown origin is thus not an uncommon problem. In the present study information about the origin and histology of liver metastases of unknown origin was compiled.

Records of all biopsies from liver metastases performed in the years 1987-1996 were retrieved from the medical database of the Department of Pathology at the University of Iceland. The biopsies came from a group of 176 patients. Ninety-two cases, in which the origin of the primary tumour was suspected or known, were excluded from the study, leaving 84 cases where the primary was completely unknown. The database of the Icelandic Cancer Society was used to gather data about the final tissue diagnosis and the location of the primary tumour when known.

The Cancer Society data revealed the location of the primary tumour in 55 of the 84 cases of liver metastases of unknown origin. The most prevalent (75%) primary tumours were cancers of the pancreas (15), lung (13) and colon/rectum (12). The tissue diagnosis was adenocarcinoma in 33 of the 55 cases. In the male patients 83% of the adenocarcinoma metastases came from the colon/rectum or pancreas. The corresponding figure for the female patients was 67%, while 20% of the tumours in females originated in the gallbladder and biliary tree.

In two thirds of the cases of liver metastases of unknown origin the primary tumour was later discovered. The most prevalent tumours were cancers in the pancreas, lung and colon/rectum. Adenocarcinoma was the tissue diagnosis in 60% of cases.