Tuberculin 16 x 18mm is considered positive for possible tuberculosis infection or previous infection. Tuberculin test, also known as PPD test, is to inject tuberculin into the skin of the inner side of the anterior wall, observe the local reaction and judge the result, which is helpful in assisting the diagnosis of tuberculosis. Tuberculin test 16×18mm is a positive result. People who have been vaccinated with BCG vaccine, who have been infected with tuberculosis in the past, and who are currently infected with tuberculosis may have a positive tuberculin test. Therefore, a positive tuberculin test does not necessarily indicate a tuberculosis infection. It is recommended that further tests such as sputum culture, antacid bacillus smear, lung CT, blood sedimentation, C-reactive protein, blood routine, etc. can be done to help clarify the condition. If tuberculosis is suspected, it is recommended to seek timely medical examination and treatment.