Pulmonary Embolism on a CXR (Picture): I Call It Happy's Lump

We are taught early and often that a diagnosis of pulmonary embolism (PE) must always be considered  in the differential diagnosis of shortness of breath or chest pain. Pulmonary emboli are blood clots that lodge in the pulmonary arteries.  Usually, but not always, they get their by traveling from the deep venous system of the legs.  A blood clot in these veins, called deep venous thrombosis (DVT), may break free and travel through the right atrium and right ventricle into the lung.

Pulmonary embolisms can present with mild symptoms of clinical insignificance to sudden out of hospital death.  Occasionally, the lucky physician will find a PE with a combination of luck and luck.  The imaging modality of  choice for diagnosing pulmonary embolism in  modern day medicine is either the CT angiogram of the chest or the ventilation/perfusion (V/Q) scan of the lungs.  Occasionally, the astute physician may raise their suspicion for pulmonary embolism by reviewing the patient's chest x-ray (CXR).

The two classic x-ray findings of a pulmonary embolism  are the Westermark sign (a dilation of the pulmonary vessels proximal to the clot with a sharp cut off distally) and Hampton's hump (a triangular infarction with the point towards the hilum).  I can honestly say I haven't seen either since my academic residency training.  Even then I only saw it during lectures on PE. What are the most common CXR findings for PE?  Here is one resource describing CXR results in a pulmonary embolism:

• 14% normal
• 68% atelectasis or parenchymal density
• 48% pleural effusion
• 35% pleural based opacity
• 24% elevated diaphragm
• 15% prominent central pulmonary artery
• 7% Westermark sign
• 7% cardiomegally
• 5% pulmonary edema

Unfortunately, this Harvard resource has failed to read The Happy Hospitalist.  If they had, they would report on the  critically important finding I am calling Happy's Lump. The first picture below is a chest xray of a patient with a pulmonary embolism confirmed by computed tomography imaging.  The second picture  is a picture of Happy's Lump, an actual visualization of the intraluminal clot on the chest x-ray. How cool is that. Happy's lump was discovered during a restrospective comparison of a chest CT with the chest x-ray.  The clot is the dark area surrounded by the white and marked by the speech bubble.  That folks is a directly visualized  pulmonary embolism on chest xray.  Don't even try telling me you see that everyday.  





I have practiced hospitalist medicine at a large community hospital system since 2003.  My experience has given me a deep appreciation for the variability of patients presenting with pulmonary embolism.  Some folks are admitted with severe hypoxemic respiratory failure and walk out without oxygen after a couple days.  Some folks come in on room air and chest pain and are found to have massive central pulmonary emboli on advanced imaging.  It is scary to think of such variation in the clinical presentation of a disease that can kill anyone, anytime and any place.

In addition to advanced imaging, cardiac enzymes, EKGs, laboratory and a detailed clinical history and physical can provide great insight into the pretest probability of a pulmonary embolism.  And after you've convinced yourself that your patient MUST have a PE or could not possibly have a PE, be prepared to get your clinical butt handed to you when  ten years of experience and seven years of formal education makes you appreciate how irrational clinical medicine can be.