Pathohistologic findings in liver metastases

Metastatic tumors are the most common malignancies of the liver. The freque ncy distribution of the primary tumor location site closely resembles the f requency distribution of primary cancers in general. Yet, due to the liver' s filter function of the portal bloodstream, metastatic tumors of the gastr ointestinal tract are overrepresented. Most metastatic tumors show a nodula r growth pattern with a demarcation of the tumor by inflammatory or fibrous reactive tissue; a diffuse metastatic tu mor spread within the sinusoids i s uncommon. Metastatic liver tumors may be the first clinically detectable manifestation of an unknown primary tumor. In these cases, the histological and immunohistochemical pattern of the metastatic tumor cells may give a c lue of the location of the corresponding primary tumor.