P40

What is the purpose of the P40 test?

P40 is an immunohistochemistry marker used primarily to identify squamous cell carcinoma, especially in lung biopsies. It helps differentiate between squamous and non-squamous histological types.


When is this test recommended?

It is used during tissue biopsy evaluations of tumors, particularly in the lungs, head, neck, and esophagus, where squamous cell carcinoma is suspected.


How is the test conducted?

The pathologist applies specific antibodies to formalin-fixed, paraffin-embedded tissue sections to visualize P40 protein expression.


What do the results mean?

Positive nuclear staining for P40 supports squamous differentiation. Negative staining suggests an alternate tumor origin.


What are the clinical implications?

Identifying tumor subtype aids in prognosis and selecting appropriate therapies, such as chemotherapy or targeted therapies.