Light micrograph showing lesions in the lung of a patient suffering from miliary tuberculosis. The blue area (upper right) and the dark green circular area (left) are regions of caseous necrosis; the white areas are alveoli (tiny air sacs) Miliary tuberculosis is an acute, generalised form of tuberculosis. It occurs when an established tubercle erodes a blood vessel wall and tubercle bacilli are discharged into the circulation, spreading the disease to other parts of the lungs and to other organs, notably the liver, kidney & spleen. In this way vast numbers of new tubercles may be produced throughout the body. Magnification: x20 at 6x7cm size.