The pathological practice for metastatic carcinoma of unknown primary - The current status and future prospect

The pathological practice for metastatic carcinoma of unknown primary is mainly to decide the histological type and suggestive primary site, which are very important for the therapeutic approach. In addition, for the morphological features with ordinary hematoxylin-eosin (HE) staining, one of the most universal and important methods is immunohistochemical staining. In recent years, detailed investigations could be performed with the combination of various primary antibodies with high organ specificity, a different pattern or amount of expression in each organ, although some cases, especially those of poor to undifferentiated carcinomas, have remained unindentified.