Tuberculin test positivity indicates

Tuberculin (Mantoux) skin test. This test is done by intradermal injection of 0.1 ml of tuberculin protein, purifiedprotein derivative (PPD). Delayed-type of hypersensitivity develops in individuals who are having or have beenpreviously infected with the tuberculous infection which is identified as an indurated area of more than 15 mm in 72hours. However, patients having disseminated tuberculosis may show negative test due to the release of a large amount of tuberculin proteins from the endogenous lesions masking the hypersensitivity test. A positive test is indicative of cell mediated hypersensitivity to tubercular antigens but doesnot distinguish between infection and disease. The test may be false positive in atypical mycobacterial infection and falsenegative in sarcoidosis, some viral infections, Hodgkin's disease, and fulminant tuberculosis. Ref: Harsh Mohan - Textbook of Pathology, 6th Edition.page no.152