A 12 mm induration (raised, firm bump) on a Mantoux Test, also known as a tuberculin skin test (TST), suggests a significant reaction at the test site. The interpretation of the test result depends on various factors, such as the person's risk factors, clinical presentation, and local guidelines. Typically, for individuals without specific risk factors, an induration size of 12 mm or greater is considered positive. However, it is important to consult with healthcare professionals familiar with the current recommendations in your region to accurately interpret the test results and determine the appropriate next steps. They may recommend further evaluation, additional tests, or treatment based on the specific circumstances and local guidelines. The interpretation of TB test results requires careful consideration of the person's medical history, risk factors, and clinical evaluation, and should always be done by healthcare professionals trained in TB management.