Cytokeratin 7

The available antibody works on formalin-fixed, paraffin embedded tissue

Immunohistochemical expression

Cytokeratin 7 is a basic cytokeratin found on many glandular and transitional epithelia.

Cytokeratin 7 is usually present in adenocarcinomas of:

• Lung

• Breast²

• Ovary; serous and endometrioid tumours

• Uterine cervical tumours

• Biliary epithelium and cholangiocarcinoma

• Transitional cell carcinoma of the bladder

It is usually absent from:

• Squamous cell carcinomas

  Colonic adenocarcinomas². Positivity may be more common in anorectal adenocarcinomas, although publications differ.

  Mucinous adenocarcinoma of the ovary

• Hepatocytes and hepatocellular carcinoma

• Prostate and prostatic adenocarcinoma

• Renal epithelial tumours¹

conventional carcinoma	0/10
chromophobe carcinoma	9/9 strong membrane staining (7 diffuse and 2 focal),
oncocytoma	8/8 focal weak to moderate cytoplasmic staining without membrane accentuation

Diagnostic utility

• The coordinate expression of cytokeratins 7 and 20 is particularly useful in identifying the primary site of adenocarcinomas.

• Renal carcinomas: differentiation of conventional carcinoma, chromophobe carcinoma and oncocytoma¹.

• Identification of ovarian granulosa cell tumours and differentiation from carcinomas (especially endometrioid carcinoma with a sex cord-like pattern)

References

¹ ME Mathers et al. Investigation of cytokeratin 7 expression in chromophobe renal cell carcinoma. Abstract 181, Pathological Society of Great Britain and Ireland January 2001.

² Jerome Marson, V., J. Mazieres, et al. (2004). "Expression of TTF-1 and cytokeratins in primary and secondary epithelial lung tumours: correlation with histological type and grade." Histopathology 45(2): 125-34.

©SMUHT/PW Bishop