Miliary pulmonary tuberculosis. False-colour chest X-ray showing fine mottling spread throughout both lungs, highlighted in pink colour. Miliary tuberculosis is an acute, generalised form of tuberculosis. It occurs when an established tubercle erodes a blood vessel wall and masses of bacilli (Mycobacterium tuberculosis) are discharged into the circulation, spreading the disease to other parts of the lungs and to other organs, notably the liver, kidney and spleen. In this way vast numbers of new tubercles may be produced throughout the body.