Pneumocystosis, Lung, Rat

Heavily infected lungs are focally to diffusely consolidated but never involve an entire lobe. The alveoli are filled with grayish material, between which the pinkish alveolar walls can be seen with a hand lens (Fig. 264). If tissue necrosis or abscesses are present, another organism should also be looked for. In contrast to consolidated lungs, the lungs are not hyperemic and are less voluminous. No fibrinous pleuritis occurs unless bacterial or fungal pneumonia is present.