How do you see tuberculosis skin test?

Tuberculosis skin test is also tuberculin test, its results according to the skin test site has no reaction and local scleroma diameter to judge, such as scleroma diameter greater than 20mm or less than 20mm, blisters, ulcers, necrosis, lymphangitis and other symptoms, generally said strong positive reaction, suggesting that there is a possibility of active lesions, need further examination /confirm/ied. If tuberculin test results are negative, said not infected with tuberculosis.