Cytokeratin 7 (CK 7)

• Focal CK7 expression in epithelioid hemangioendothelioma of the liver. Note the strong staining of the adjacent bile duct.
• CK7 expression in epithelioid hemangioendothelioma of the liver.
• Focal CK7 expression in epithelioid hemangioendothelioma of the liver. Note the strong staining of the adjacent bile duct.
• CK7 expression in epithelioid hemangioendothelioma of the liver.
• CK7 expression in epithelioid hemangioendothelioma of the liver.
• CK7 expression in epithelioid hemangioendothelioma of the liver.
• Cytokeratin 7 expression in benign bile ducts.
• Cytokeratin 7 expression in proliferating bile ductules.
• Cytokerating 7 expression in lung with lambertosis.
• Cytokerating 7 expression in lung with lambertosis.
• CK 7 highlighting the neoplastic cells in Paget's disease of the breast

1/11

Staining Pattern

• Cytoplasmic staining

Expression in Normal Tissues

• Bile ducts
• Pancreatic ducts

Expression in Neoplastic Entities

Benign

Tumor name	% Positive Staining	Number of Cases

Intermediate/Uncertain Malignant Potential

Tumor name	% Positive Staining	Number of Cases

Malignant

Tumor name	% Positive Staining	Number of Cases
Renal cell carcinoma (papillary, chromophobe)	95%, 100%	19/20, 11/11
Pulmonary adenocarcinoma and a subset of pulmonary squamous cell carcinoma
Carcinomas of the breast, thyroid, salivary glands, endometrium
Mesothelioma
A subset of gastric carcinomas
A subset of esophageal carcinomas

Pertinent Negatives

This antigen is typically NOT expressed by the following entities:

Common Pitfalls

• Epithelioid hemangioendothelioma and angiosarcoma can both express cytokeratins, including CK 7, and this can lead to a misdiagnosis of carcinoma. Use of CD31 and CD34 can help with this distinction, as both markers are usually negative in carcinomas.