photomicrograph A) Immunostaining showing CK7 positivity in tumour cell groups. B): Immunostaining showing CEA positivity in tumour cell groups. C): Immunostaining showing CK20 negativity in tumour cell groups. D): Immunostaining for CDX2. There is positive staining in normal colonic mucosa (single arrow) whereas the tumour beneath the mucosa stains negative (two arrows).
Birla et al. World Journal of Surgical Oncology 2008 6:47 doi:10.1186/1477-7819-6-47