Cervical immunohistochemistry p40 is an indicator for pathologists to determine the origin of the tissue, and if positive, suggests squamous cell carcinoma of the cervix. Squamous cell carcinoma and adenocarcinoma of the cervix are usually determined by immunohistochemistry, which is a further screening test for cervical lesions. Cervical P40 protein is a commonly used squamous epithelial marker by immunohistochemistry, and immunohistochemistry is usually utilized in oncologic pathology to determine if the tissue is squamous. Positive suggests squamous cervical cancer, mostly seen in low differentiated squamous cervical cancer. P40 is a protein, and immunohistochemistry is used to determine the source of tissue tumors by identifying antigens (peptides and proteins) within the cells of cervical tissues through a chemical reaction that causes a chromogenic agent labeled with an antibody to develop color. A positive cervical immunohistochemistry p40 is generally indicative of squamous cell carcinoma of the cervix, while a negative result indicates a high likelihood of adenocarcinoma. Patients should maintain a good state of mind and avoid staying up late before having immunohistochemistry.