A 67 y.o. male presents with shortness of breath

what is your differential?

Our patient has unilateral pulmonary edema. A right upper lobe infiltrate is strongly associated with severe mitral regurgitation which is what our patient had. The regurgitation jet is directed toward the right superior pulmonary vein increasing the pressure in the RUL.

Unilateral pulmonary edema can occur in other circumstances. The most important thing is to recognize which lung is abnormal.

If the abnormal lung is the one with the infiltrate

Severe MR

Pulmonary vein occlusion

Re-expansion pulmonary edema- occurs after chest tube placement for a pneumothorax.

Congenital or surgical right-to left shunt (e.g. Blalock Taussig shunt)

If the abnormal lung is on the clearer side

Unilateral pulmonary embolism- Westermark’s sign, shows decreased vascularity in the lung with the PE.

Swyer-James syndrome-  is unilateral lung hyperlucency due to infectious bronchiolitis as a child.

Unilateral emphysema/bullae

Don’t be fooled by a large bulla; putting in a chest tube in this case can cause a bronchopleural fistula

Congenital  hypoplasia of the pulmonary artery. can also cause differences between the two lungs.

TAKE HOME PEARLS

1 .In all these cases an old CXR is your friend.  Our patient had a previous cxr five days earlier which had clear lungs. He was diuresed and discharged.

2.Compare the two sides and decide which is the abnormal side.

3.Always look at the “I” of the CXR; the hidden areas behind the clavicles, in the central mediastinum, and along the diaphragms.

You would not miss this lesion if you look at the “I” of the cxr. In this case the lateral shows the lesion since the vertebra should be more lucent as you travel down the spine.

Attias D, Mansencal N, Auvert B et al. Prevalence, characteristics and outcomes of patients presenting with cardiogenic unilateral pulmonary edema. Circulation 2010;122(11):1109-15.

Miyatake K, Nimura Y, Sakakibara H, et al. Localisation and and direction of mitral regurgitant flow in mitral orifice studied with combined use of ultrasonic pulsed doppler technique and two dimensional echocardiograpy. Br Heart J. 1982;48(5):449-58.

Waseem M, Jone J, Brutus S, et al. Giant bulla mimicking pneumothorax The Journal of Emergency Medicine Vol 29(2)August  2005:155-158.

Howarth T, Missed lung lesions: side-by-side comparison of chest radiography with MDCT. Diseases of the chest, breast, heart and vessels 2019-2022: Diagnostic and interventional Imaging (Internet)