Angioarchitecture and blood supply of micro- and macrometastases in human livers. An anatomic-pathological investigation using injection-techniques.

The histological and stereoscopical appearance of the metastatic vascular tree was examined in a series of 23 human metastatic livers using injection techniques. All metastases showed an abnormal 'construction-concept' of vascularization, never imitating the normal angioarchitecture of the liver parenchyma. 17 of 22 arterial injected livers contained hyper-, and 5 hypovascularized metastases. Two main types of hypervascularized metastases could be detected: a central type with blood supply via a main arterial 'hilus-like' branch, and a peripheral type with multiple arterial vessels infiltrating from the metastatic surrounding. Of 13 livers injected via the portal vein, 11 showed a portal supply of the metastases. Portal tumor thrombi were a frequent finding, possibly indicating a retrograde portal local tumor spread within the liver. No larger branches of the hepatic vein could be found in any metastases which were injected via the hepatic veins; all showed typical signs of compression, displacement and destruction. Micrometastases were found in the direct surroundings of almost half of all macrometastases. Up to a size of 100-200 microns they appeared to be mainly supplied by sinusoidal blood. With continuing growth, newly built capillaries could be shown in the direct surroundings of some of the micrometastases.