SATB2 is a supplementary immunohistochemical marker to CDX2 in the diagnosis of colorectal carcinoma metastasis in an unknown primary.

CDX2 is routinely used for identifying gastrointestinal origin of metastatic adenocarcinomas; but a high percentage of other carcinomas also show positivity with this antibody. SATB2 is a new immunohistochemical marker with a few studies showing that it is specifically expressed in a large majority of colorectal adenocarcinomas. We assessed SATB2 along with CDX2 in patient material with metastasis in order to determine whether the primary site could be identified as 'colon-rectum'.

[Breast cancer metastasis to the colon].

A 69-year-old woman was admitted with diarrhoea, anaemia and elevated C-reactive protein. She was diagnosed with metastases of a carcinoma to the colon; the immunohistochemical profile made lobular breast cancer the most likely primary tumour. But despite thorough examination, such tumour was never found.