Final answer:
A positive tuberculosis skin test does not necessarily indicate active tuberculosis, but rather exposure and a cellular immune response to M. tuberculosis.
Step-by-step explanation:
A positive tuberculosis skin test does not necessarily indicate that the patient has active tuberculosis. The test, known as the Mantoux tuberculin skin test, is used to screen for potential TB exposure. When bacterial proteins from M. tuberculosis are injected into the skin, a positive test is indicated by a raised red area called an induration, which is a result of the cellular immune response to the bacteria. This means that the patient has been exposed to the bacteria and exhibits a cellular immune response, but it does not confirm active infection.