<prompt> Answer this question truthfullyWhat can be seen on a chest x-ray in a case of Pneumocystis jirovecii pneumonia?  <response>: <reason> There is increased opacification whiteness in the lower lungs on both sides, characteristic of Pneumocystis pneumoniaThe diagnosis can be confirmed by the characteristic appearance of the chest x-ray which shows widespread pulmonary infiltrates, and an arterial oxygen level pO 2 strikingly lower than would be expected from symptoms. 