CT Case 087
A 28-year-old female presents to emergency with anterior chest pain and a dry cough.
A CXR is performed
Describe and interpret the X-rays
Chest x-ray demonstrates a mediastinal mass obscuring the upper part of left heart border (loss of normal silhouette of left cardiac border), which is a clue for localising the lesion into the anterior mediastinum.
There are no calcifications or fat density areas within the mass.
There is mild mass effect on the carina, pushing it to right side.
Lateral view of the chest radiograph demonstrates obliteration of the retrosternal airspace confirming an anterior mediastinal mass. The retrosternal airspace is the lucency seen behind the sternum and anterior to the ascending aorta.
The patient is subsequently taken for CT.
Describe and interpret the CT scans
CT demonstrates a large soft tissue density – an anterior mediastinal mass with interspersed necrotic areas within. The lesion is abutting the mediastinal vessels (SVC, aortic arch and pulmonary artery) without encasement.
Anteriorly, the lesion is abutting the sternum and left sided anterior ribs without bone destruction or chest wall invasion.
It is important to look for pleural deposits and bony destruction as this can help in narrowing the differential.
Clinical Pearls
Anterior mediastinal masses are most commonly thymomas, teratomas, thyroid disease with retrosternal goitre and lymphomas.
Thymoma is the most common primary neoplasm of the anterior mediastinum but comprises less than 1% of all adult malignancies.
Initially it was thought that this was a thymoma, based on the CT appearance of a lobular mass with necrotic foci, which is typically seen in thymoma. It was believed that lymphoma was unlikely to be the cause as usually necrosis only develops after chemotherapy has commenced.
However, open biopsy ultimately revealed that this was a primary mediastinal B-cell lymphoma. These are commonly seen in middle aged adults with a mean age of 30 years. In B-cell lymphoma areas of low attenuation necrosis are commonly seen. She is currently undergoing chemotherapy regime.
References
- Juanpere S, Cañete N, Ortuño P, Martínez S, Sanchez G, Bernado L. A diagnostic approach to the mediastinal masses. Insights Imaging. 2013 Feb;4(1):29-52.
TOP 100 CT SERIES
Emergency Medicine Education Fellow at Liverpool Hospital NSW. MBBS (Hons) Monash University. Interests in indigenous health and medical education. When not in the emergency department, can most likely be found running up some mountain training for the next ultramarathon.
Dr Leon Lam FRANZCR MBBS BSci(Med). Clinical Radiologist and Senior Staff Specialist at Liverpool Hospital, Sydney
Sydney-based Emergency Physician (MBBS, FACEM) working at Liverpool Hospital. Passionate about education, trainees and travel. Special interests include radiology, orthopaedics and trauma. Creator of the Sydney Emergency XRay interpretation day (SEXI).
Provisional fellow in emergency radiology, Liverpool hospital, Sydney. Other areas of interest include paediatric and cardiac imaging.