Minimal solid tumor involvement of regional and distant sites

Immunohistochemistry and other special techniques have been reported to be able to identify carcinoma cells in metastatic sites in which they had not been detected by conventional histology. However, many pathologists order the histochemistry before examing the hematoxylin and eosin (H&E) preparations. Thus there is truly a need for a set of guidelines regarding the size and site of metastatic deposits, as well as further research to determine the clinical significance of minute metastases not detectable with H&E preparations. See also pages 2668–73.