IMMUNOHISTOCHEMISTRY, CK 5 / 6

The IHC – CK5/6 (Cytokeratin 5/6) test is an immunohistochemistry-based diagnostic assay used to detect cytokeratin 5 and cytokeratin 6 proteins in tissue samples. Cytokeratins are structural proteins found in epithelial cells, and CK5/6 is particularly associated with basal and squamous epithelial cells.

This test is widely used in surgical pathology to identify and classify squamous cell carcinomas and other epithelial tumors. CK5/6 staining helps pathologists determine the origin and differentiation of tumor cells, making it especially valuable in distinguishing squamous cell carcinoma from adenocarcinoma in organs such as the lung.

Benefits of the Test

• Helps diagnose squamous cell carcinoma
• Assists in identifying epithelial cell origin
• Differentiates squamous tumors from adenocarcinomas
• Supports accurate tumor classification
• Helps guide oncology treatment planning

Why Doctors Recommend This Test

Doctors recommend the IHC CK5/6 test when there is suspicion of epithelial malignancies, particularly squamous cell carcinoma. It is commonly used in:

• Diagnosis of lung squamous cell carcinoma
• Evaluation of head and neck cancers
• Assessment of skin and epithelial tumors
• Mesothelioma diagnostic panels
• Classification of poorly differentiated carcinomas

CK5/6 is often used together with markers such as P63, P40, TTF-1, Calretinin, and EMA to improve diagnostic accuracy and determine tumor subtype.

Preparation Before Test

No special preparation is required for this test. Important considerations include:

• The test is performed on a biopsy or surgical tissue sample
• No fasting or medication restrictions are necessary
• Clinical history and imaging findings may support interpretation

Normal Reporting Time

The typical turnaround time is 3 to 5 working days, depending on specimen processing and laboratory workflow.

Who Should Take This Test

• Patients with suspected squamous cell carcinoma
• Individuals with lung tumors requiring subtype classification
• Cases of epithelial tumors with uncertain origin
• Patients undergoing biopsy evaluation for cancer diagnosis
• Oncology patients requiring immunohistochemistry profiling

The IHC CK5/6 test is an important diagnostic tool in oncology and surgical pathology. By identifying squamous and basal epithelial differentiation, it helps clinicians accurately classify tumors and select appropriate treatment strategies.

Clinical Significance

CK5/6 is frequently used in the diagnosis and classification of:

• Squamous cell carcinoma of the lung
• Head and neck squamous cell carcinoma
• Cervical squamous cell carcinoma
• Mesothelioma
• Basal-type epithelial tumors
• Poorly differentiated carcinomas