Pneumocystis Carnii-CT

Clinical Profile : HIV positive status. There is presence of ground glass haziness with interstitial interlobular  and intralobular septal thickening noted in both lungs with symmetrical and perihilar distribution, sparing the lung peripheries. No evidence any cystic lucencies are noted. Possibility of Pneumocystis Carnii. Case  Submitted by Dr Swati Shah, MD, FRCR & Dr Sumer Sethi.

Features  of P. Carnii on CT include:

• ground-glass pattern
• predominantly involving perihilar or mid zones
• there may be a mid, upper or lower zone predilection depending on whether the patient is on prophylactic aerosolised medication , if they are, then the poorly ventilated upper zones are prone to infection , whereas in those who are not the lower zones are more frequently involved
• reticular opacities or septal thickening may also be present
• a crazy paving pattern may therefore be seen when both ground-glass opacies and septal thickening are superimposed on one another
• pneumatocoeles 
• pleural effusions are rare