Colorectal adenocarcinoma, cytokeratin immunostaining

Colonic adenocarcinomas1:

	n	CK7+	CK20+	CK7+/CK20-	CK7-/CK20+	CK7+/CK20+	CK7-/CK20-
primary colon carcinoma1	51	16%	96%	0	80%	16%	4%
primary colon carcinoma (same cases as ovarian metastases below)2	15	47% (7/15)	87% (13/15)
primary colon carcinoma3	46	29% (13/46)	87% (40/46)
primary colon carcinoma4	75		99%(74/75)
primary colon carcinoma5	21		20
total for primary colon carcinoma	112	25% (28/112)	94% (176/187)

metastatic colon carcinoma1	26	31%	100%	0	69%	31%	0
colon carcinoma metastatic to ovary 2	17	24% (4/17)	76% (13/17)
metastatic colon carcinoma4	27		96% (27/28)
total for metastatic colon carcinoma	43	28% (12/43)	93% (66/71)

Positivity for CK7 may be more common in anorectal adenocarcinomas, although publications differ:

	CK7+/CK20+	CK7+/CK20-	CK7-/CK20+	CK7-/CK20-
Non-neoplastic anorectal mucosa	6/189	3/189	9/189	0/189
Non-neoplastic anal glands(in haemorrhoroidectomy specimens)	0/1210	12/1210	0/1210	0/1210
Rectal adenoma	1/79	2/79	4/79	0/79
Rectal adenocarcinoma	26/359, 4/3010	0/359, 0/3010	9/359, 26/3010	0/359, 0/3010
Perianal Paget's disease and associated adenocarcinoma	4/411, 3/3(the Paget's disease)13	0/411	0/411	0/4\|
Anal gland carcinoma	1/712	6/712	0/712	0/712
Colonic adenocarcinoma proximal to rectum	3/119

Cytokeratin 20 is more often negative in colorectal carcinomas with neuroendocrine differentiation7, in high grade7,8 and right-sided tumours8. Cytokeratin 7 positivity is also more common in high grade tumours8. Cytokeratin 20 expression is reduced in colorectal carcinomas with high levels of microsatellite instability6:

	microsatellite unstable	microsatellite stable
mean percentage of cells positive for CK7	7±56	6±56
mean percentage of cells positive for CK20	37±86	84±66
CK7-/CK20+	12/226	17/226
CK7+/CK20+	3/226	3/226
CK7+/CK20-	1/226	0/226
CK7-/CK20-	6/226	2/226
Pancytokeratin cocktail	22/226	22/226

References

1 Loy TS, Calaluce RD. Utility of cytokeratin immunostaining in separating pulmonary adenocarcinomas from colonic carcinomas. Am J Clin Pathol 1994;102:764-767.

2 CCAP Wauters et al. Keratins 7 and 20 as diagnostic markers of carcinomas metastatic to the ovary. Hum Pathol 1995;26:852-855.

3 JH Lagendijk et al. Tracing the origin of adenocarcinomas with unknown primary using immunhistochemsitry: differential diagnosis between colonic and ovarian carcinomas as primary sites. Hum Pathol 1998;29:491-497.

4 Miettinen M. Keratin 20: immunohistochemical marker for gastrointestinal, urothelial and Merkel cell carcinomas. Mod Pathol 1995;8:384-388.

5 Yatabe, Y., T. Koga, et al. (2004). "CK20 expression, CDX2 expression, K-ras mutation, and goblet cell morphology in a subset of lung adenocarcinomas." J Pathol 203(2): 645-52.

6 McGregor, D. K., T. T. Wu, et al. (2004). "Reduced expression of cytokeratin 20 in colorectal carcinomas with high levels of microsatellite instability." Am J Surg Pathol 28(6): 712-8.

7 Kende, A. I., N. J. Carr, et al. (2003). "Expression of cytokeratins 7 and 20 in carcinomas of the gastrointestinal tract." Histopathology 42(2): 137-40.

8 Park, S. Y., H. S. Kim, et al. (2002). "Expression of cytokeratins 7 and 20 in primary carcinomas of the stomach and colorectum and their value in the differential diagnosis of metastatic carcinomas to the ovary." Hum Pathol 33(11): 1078-85.

9 Zhang, P. J., M. Shah, et al. (2003). "Cytokeratin 7 immunoreactivity in rectal adenocarcinomas." Appl Immunohistochem Mol Morphol 11(4): 306-10.

10 Ramalingam, P., W. R. Hart, et al. (2001). "Cytokeratin subset immunostaining in rectal adenocarcinoma and normal anal glands." Arch Pathol Lab Med 125(8): 1074-7.

11 Goldblum, J. R. and W. R. Hart (1998). "Perianal Paget's disease: a histologic and immunohistochemical study of 11 cases with and without associated rectal adenocarcinoma." Am J Surg Pathol 22(2): 170-9.

12 Hobbs, C. M., M. A. Lowry, et al. (2001). "Anal gland carcinoma." Cancer 92(8): 2045-9.

13 Nowak, M. A., P. Guerriere-Kovach, et al. (1998). "Perianal Paget's disease: distinguishing primary and secondary lesions using immunohistochemical studies including gross cystic disease fluid protein-15 and cytokeratin 20 expression." Arch Pathol Lab Med 122(12): 1077-81.

This page last revised 11.7.2004.