Miliary tuberculosis. Light micrograph of tissue from a liver in a case of miliary tuberculosis. Tuberculosis (TB) is a disease caused by infection with Mycobacterium tuberculosis bacteria. The bacteria are usually inhaled in water droplets, and can progress from the lungs to the lymphatic system, as well as to other body organs. Miliary TB is the spread of the TB bacteria through the bloodstream, in this case from the lungs. Langerhans giant cells (bright pink) are also seen here.