CDX are homeobox genes essential to intestinal organogenesis and encode nuclear transcription factors6. CDX-2 is analogous to the Drosophila gene caudal. Two genes have been identified in humans (CDX-1 and CDX-2) and a third gene (CDX-4) in mice9. CDX2-knockout mice show that the absence of the gene (-/-) is lethal in utero, while heterozygotes (+/-) show focal loss of intestinal differentiation22 and develop hamartomas and neoplasms of the colon9. CDX-1 appears to be responsible for proliferation and CDX-2 for differentiation of intestinal epithelium8. CDX-2 appears to promote expression of the proglucagon gene7, colon carbonic anhydrase-130, sucrase-isomaltase23 and lactase23, and to act as a tumour suppressor gene, downregulated in colonic carcinoma10. It interacts with the tumour suppressor genes APC12 and E-cadherin13, as well as bcl-211.
A monoclonal antibody is available which is effective on formalin-fixed paraffin-embedded tissue. Immunoreactivity for CDX-2 is nuclear, accompanied by faint cytoplasmic staining in some cases. Recently, two substantial paper on the diagnostic use of CDX-2 has been published1,2; it appears promising and the findings of these papers are underpinned by more basic biological papers on this homeobox gene. The subject has been reviewed17.
The use of the proprietary Trilogy antigen retrieval buffer containing EDTA gives a higher rate of staining in lung tumours than does a citrate buffer: the results with the Trilogy buffer accord more closely with the assessment of CDX-2 gene expression30.
normal tissues:
with the exception of those listed below, normal tissues are NEGATIVE for CDX-223.
CDX-1 and CDX-2 are both broadly expressed in the fetus but by the early neonatal period become restricted to the small and large bowel and pancreas. CDX-1 is predominantly expressed in the base of crypts and CDX-2 higher, in the crypt tip5 and villi. CDX-2 positivity is seen in intestinal epithelial cells from duodenum to rectum23, including absorptive, goblet, (neuro)endocrine26 and Paneth cells. The CDX-2 gene is more strongly expressed in the small intestine and caecum, less intensely in the distal colon5.
Scattered cells are positive in pancreatic ductules23. Scattered cells are occasionally positive in the gallbladder (1 of 5 cases)2.
There is no nuclear reactivity in liver, stomach22 (except within intestinal metaplasia), thyroid, parathyroid, adrenal, pancreatic islets, alveolar cells, bronchial epithelium, urogenital tract, squamous epithelium (skin, larynx, oesophagus[except within intestinal metaplasia], vagina, cervix), lymphoid tissue, CNS and peripheral nerves. Cytoplasmic staining for CDX-1 has been reported in scattered cells in the gastric antrum22. Supra-nuclear Golgi staining occurs in the normal gastric glands and in most of the cells of the foveolar epithelium of the antrum22.
Gastric intestinal metaplasia shows ectopic overexpression of both CDX-1 (in 47/523 and 18/1822 cases) and CDX-2(in 41/483 and 17/1822 cases): the CDX-2 immunoreactivity is not abolished by the eradication of Helicobacter pylori19. There is no difference in the staining between complete and incomplete intestinal metaplasia22. Diffuse cytoplasmic and Golgi staining for both CDX-1 and CDX-2 may accompany the nuclear staining22. In gastritis, the mucosa shows fine granular cytoplasmic staining in both the presence and absence of intestinal metaplasia19. Expression of CDX-2 is reportedly greater in complete intestinal metaplasia than it is in incomplete intestinal metaplasia (with its greater risk of progression to carcinoma) or in dysplasia29:
Reference 29 |
CDX-2 score |
||
Normal gastric mucosa |
0 |
||
Complete intestinal metaplasia |
8 |
||
Incomplete intestinal metaplasia |
6 |
||
Gastric dysplasia |
3.9 |
||
Gastric carcinoma |
3.1 |
||
The normal oesophageal mucosa is negative18. Barrett's oesophagus shows strong nuclear and fine granular cytoplasmic staining, while inflamed oesophagus without intestinal metaplasia shows only fine granular cytoplasmic staining18.
Glandular metaplasia of the oesophagus without goblet cells |
17/4528 |
||
Strips of superficial Alcian blue positive columnar mucosal cells devoid of goblet cells |
0/1128 |
||
Barrett's oesophagus (intestinal metaplasia with goblet cells) |
45/4528 |
||
From this study it was argued that CDX-2 identifies form fruste intestinal metaplasia prior to the development of goblet cells!28
Granular cytoplasmic positivity has been reported in epithelial mucosa in the inflamed gallbladder and nuclear positivity in intestinal metaplasia of the gallbladder25.
Neoplasms:
One paper uses a cutoff of 25% of tumour cells positive2. In order to render the papers comparable, I have presented the results showing any degree of positivity for CDX-2 as positive.
Adenocarcinomas |
Colorectum |
58/601, 30/301, 75/752, 13/1314, 84%15, 100%16, 21/2121, 60/6023, 24/2524, 13/1330, 39/4750 |
Colorectal large cell minimally differentiated carcinoma |
2/1524 |
|
Gastro-oesophageal |
76/16423 |
|
Oesophagus |
6/92, 4/514, 4/530, 2/2150 |
|
Stomach |
||
Duodenum |
4/42 |
|
Ampullary carcinoma |
4/623, 4/630, 1/650 |
|
Pancreas |
||
Gallbladder, cholangiocarcinoma |
||
Hepatocellular |
0/122, 0%15, 0%16, 0/1223, 0/650 |
|
Ovary, mucinous adenocarcinoma |
||
Ovary, serous adenocarcinoma |
0/51, 2%15, 2/4123, 0/530, 0/1850 |
|
Ovary, non-mucinous, NOS |
1/362, 0/514 |
|
Ovary, endometrioid |
3/1023 |
|
Ovary, clear cell |
1/224 |
|
Ovary, undifferentiated |
0/723 |
|
Endometrial |
1/1014, 9%15, 4/2223, 1/1030, 0/1050 |
|
Endocervical |
no reports yet |
|
Breast |
0/201, 0/101, 0/342, 0/2214, 0%15, 0/7023, 0/1049, 0/2930, 0/3550
|
|
Prostate |
||
Bladder adenocarcinoma |
3/32 |
|
Kidney |
||
Sinonasal intestinal type |
no reports yet. |
|
Thyroid |
||
Adenoma |
Duodenum |
|
Colorectum |
98%15 |
|
Ovary, mucinous cystadenoma |
1/132 |
|
Ovarian benign mucinous tumour of endocervical type |
0/4720 |
|
Ovarian benign mucinous tumour of intestinal type |
3/320 |
|
Ovary, mucinous borderline tumour |
1/42 |
|
Gastrointestinal neuroendocrine tumours |
Gastric neuroendocrine hyperplasia |
3/526 |
Gastrointestinal carcinoid, various sites
|
||
Gastric well differentiated neuroendocrine tumour |
5/526 |
|
Gastric neuroendocrine carcinoma |
6/726 |
|
Duodenal well differentiated neuroendocrine tumour |
4/426 |
|
Ileal well differentiated neuroendocrine tumour |
14/1426 |
|
Small intestinal neuroendocrine carcinoma |
2/226 |
|
Appendiceal well differentiated neuroendocrine tumour |
6/626 |
|
Colonic well differentiated neuroendocrine tumour |
0/126 |
|
Colonic neuroendocrine carcinoma |
5/526 |
|
Rectal well differentiated neuroendocrine tumour |
7/926 |
|
Pancreatic islet cell tumours, NOS |
4/1423 |
|
Pancreatic functioning well differentiated neuroendocrine tumour |
0/1326 |
|
Pancreatic non-functioning well differentiated neuroendocrine tumour
|
14/4826 |
|
Pancreatic islet cell tumour |
4/1423 |
|
Liver neuroendocrine carcinoma |
1/126 |
|
Lung primaries |
Neuroendocrine hyperplasia |
0/526 |
0/101, 0/112, 3/4121, 0/1323, 0/750 |
||
0/521 |
||
Adenocarcinoma NOS |
||
Acinar adenocarcinoma |
0/371 |
|
0/61 |
||
Bronchoalveolar carcinoma |
0/281 |
|
0/101, 0/621, 0/123 |
||
non-small cell and NOS |
4/332, 1<1%15 |
|
Large cell neuroendocrine carcinoma |
3/821, 5/86 |
|
0/11 |
||
Carcinoma other than adenocarcinoma |
3/2930 |
|
0/51, 0/72, 0/2824, 0/650 |
||
Other lung tumours |
0/51 |
|
0/21 |
||
0/11 |
||
Blastoma |
0/21 |
|
Other carcinomas |
transitional cell carcinoma of bladder |
|
head and neck squamous cell carcinoma |
0/132 |
|
oesophageal squamosu cell carcinoma |
0/750 |
|
sarcomatoid carcinoma, various sites |
0/1423 |
|
Other neuroendocrine tumours |
Bladder neuroendocrine carcinoma |
4/1026 |
Uterine neuroendocrine carcinoma |
2/326 |
|
Prostatic neuroendocrine carcinoma |
2/526 |
|
Breast neuroendocrine carcinoma |
1/326 |
|
1/1526 |
||
Salivary gland |
0/62 |
|
0/423 |
||
0/1723 |
||
0/323 |
||
low grade carcinoma |
0/62 |
|
neuroendocrine carcinoma |
1/326 |
|
Germ cell tumours |
Dysgerminoma |
1/423 |
Embryonal carcinoma |
0/323 |
|
Seminoma |
0/623 |
|
Yolk sac tumour |
4/523 |
|
Ovary, granulosa cell tumour |
0/823 |
|
0%15, 0/123 |
||
Paraganglioma |
0/626 |
|
0/426 |
||
Adrenal cortical adenoma |
0/126 |
|
Thyroid carcinomas |
0/1226 |
|
Parathyroid adenoma |
0/226 |
|
There is loss of CDX-2 expression in a small proportion of colonic carcinomas and in some series, poorly differentiated adenocarcinomas in patients with microsatellite instability tend to show less expression than better differentiated tumours1, although others have not found a correlation with the grade of tumour2.
CDX-1 was expressed in 51 of 69 gastric adenocarcinomas and more often in intestinal than diffuse type gastric carcinomas3.
CDX-2 positivity in lung carcinomas is associated with CK20 positivity, male gender, size >30 mm and lack of TTF-1 expression21. Positivity of adenocarcinomas for CDX-2 and CK20, albeit with retention of CK7, at sites outside the gastrointestinal tract, may be a manifestation of the acquisition of an intestinal phenotype.
Positivity for CDX-2 occurs in a minority of neuroendocrine carcinomas outside the gastrointestinal site, without an apparent relation to the site26.
Diagnostic utility
Identification of the primary site of a metastatic adenocarcinoma, and differentiation from a primary adenocarcinoma of lung, in combination with TTF-1, CK7 and CK20. CDX2 does not reliably differentiated between colorectal, other gastrointestinal, mucinous ovarian and bladder adenocarcinomas. It may be useful in combination with villin: if negative for both, very unlikely to be from a gastrointestinal primary. If there is positivity for CDX2 (with or without villin immunoreactivity) it is likely to be from a colorectal primary. However, note the caveats associated with primary mucinous tumours of the lung and intestinal type sinonasal adenocarcinoma. Variable staining for both CDX2 and villin suggests origin from elsewhere in the gastrointestinal tract2. Nuclear immunoreactivity for CDX2 and TTF-1 is particularly useful in interpreting cytological specimens from metastatic colorectal carcinoma to lung1. As a member of a panel to differentiated primary ovarian endometrioid/mucinous carcinoma of the ovary from metastatic colorectal carcinoma.
Identification of the site of origin of a well differentiated neuroendocrine tumour: tumours of the ileum and appendix are strongly positive, those of the stomach, colorectum and pancreas are variable and all others are negative26. For high grade tumours, most gastrointestinal neuroendocrine carcinomas are positive, but so are a minority of those from other sites26.
Possibly in the identification of high-risk intestinal metaplasia of the gastric mucosa29.
There is little published data on the diagnostic value of CDX-13.
References
4 Rossi G, presentation to Pulmonary Pathology Club, Chester, UK, 13.6.03; paper submitted.
14 Mazziotta RM, Borczuk AC, Alexis D et al. Differential expression, by immunohistochemsitry, of CDX2 transcription factor in various adenocarcinomas. Mod Pathol 2003;15:127A. [abstract] [These cases appear to be expanded upon in reference 30.]
15 Kaimaktchiev V, Firnhofer S, Sauter G et al. Selective staining of gastrointestinal adenocarcinoma by the homeobox intestinal differentiation factor CDX2. Mod Pathol 2003;15:123A. [abstract]
16 Furlanetto A, Orvieto E, Laurino L et al. Mod Pathol 2003;15:273A.
49 Strickland-Marmol LB, Khoor A, Livingston SK, et al. Utility of tissue-specific transcription factors thyroid transcription factor 1 and Cdx2 in determining the primary site of metastatic adenocarcinomas to the brain. Arch Pathol Lab Med 2007; 131:1686-90 FULL TEXT
50 Dennis JL, Hvidsten TR, Wit EC, et al. Markers of adenocarcinoma characteristic of the site of origin: development of a diagnostic algorithm. Clin Cancer Res 2005; 11:3766-72 FULL TEXT
This page last revised 26.11.2008.
©SMUHT/PW Bishop