The tuberculosis screening skin test, also known as the PPD test and also known as the tuberculin test, is of clinical importance in screening for tuberculosis. The tuberculin test is mainly used to determine the presence of Mycobacterium tuberculosis infection, so the tuberculin test has a relatively important clinical significance in ruling out tuberculosis. However, this test has certain limitations, as some patients may have a positive immune reaction after BCG vaccination, and patients with HIV infection, tumors, and serious infections may also have a positive reaction.