Case, content, original post by Lauren Brown, MD
Expert radiology interpretation by David Godwin, MD
Identify abnormal aortic size on chest x-ray.
40 yo man from Mexico with 15 pack-year smoking history who presented with five weeks of subjective fevers, dyspnea, and pleuritic chest discomfort which did not respond to antimicrobial treatment. He denies known tuberculosis exposure and has been living in the U.S. for the last 3 years.
Vital signs and physical examination are normal.
How do you determine normal aortic size on chest x-ray?
- The normal aorta width (when measured from the lateral aspect of the trachea to aortic edge/lung) should be <3cm. Aortic width can increase with age or hypertension, but this patient’s young age suggests these are less likely.
- On a lateral chest x-ray, the area inferior to the bronchus intermedius should be radiolucent. Opacity here (forming a complete circle with central opacity) is known as the “donut sign” and indicates presence of lymphadenopathy or mass.
DIAGNOSIS AND OUTCOME
CTA chest showed severe wall thickening of the ascending aorta and aortic arch consistent with aortitis as well as presence of lymphadenopathy.
An extensive evaluation was performed. Bacterial and AFB blood cultures had no growth, HIV testing negative, and ANA, rheumatoid factor, ANCA, and syphilis serologies were negative. Black-blood MR of aortic vasculature was not consistent with Takayasu. Bronchoscopy was negative for bacterial, fungal, AFB stain and culture. Immunoglobulin levels with IgG subclasses were normal. Mediastinoscopy with lymph node biopsy confirmed tuberculosis and patient was treated with RIPE+steroids with improvement on subsequent imaging.
TAKE HOME POINTS
- Aortic silhouette > 3 cm on CXR is suggestive of aortic enlargement, which can be seen in aortic dissection, aortic aneurysm or aortitis. A CTA is needed to differentiate between these abnormalities.
Causes of Aortitis
- Most common cause of aortitis is large-vessel vasculitis
- Infectious causes include tuberculosis, syphilis, staphylococcus species, streptococcus pneumonia, salmonella, and other bacteria
- May be idiopathic/isolated