Archived case 198 · February 26-March 4, 2016
30 y/o female, Routine physical
Describe the abnormality. What are some imaging features that might help localize a lesion to the anterior, posterior, or middle mediastinal compartments on radiographs?
Imaging findings: PA and lateral chest radiographs demonstrate a roughly 2 cm rounded density in the left paraspinal/retrocardiac space on frontal view. It appears to localize to the middle mediastinum on the lateral projection. Contrast-enhanced axial and coronal CT slices demonstrate a rounded, low attenuating structure adjacent to the lower esophagus. There is no internal enhancement or calcification. The lesion is also well defined and not particularly aggressive appearing. PET-CT fusion axial image demonstrates no hypermetabolic activity within the lesion. Answer Diagnosis: Esophageal Duplication Cyst
Esophageal Duplication Cyst
Answer
Diagnosis: Esophageal Duplication Cyst
Discussion: Felson divides the mediastinum into three compartments. The anterior compartment lies between the posterior aspect of the sternum and the anterior border of the trachea. The middle compartment continues from the anterior tracheal border to 1 cm posterior to the anterior margin of the vertebral bodies. The posterior compartment continues posteriorly from there .
Helpful tips for locating mediastinal masses on frontal radiographs:
Pulmonary vs Mediastinal: Only lung parenchymal masses will demonstrate air bronchograms . If the mass forms an acute angle with the medial edge of the lung, it most likely arises from the lung. If the angle is obtuse, the mass most likely arises from the mediastinum.
Cervicothoracic sign: The clavicles define the superior border of the anterior mediastinum. Thus, a mass projecting above the clavicles is located in the posterior mediastinum.
Hilum overlay sign: Masses arising from the hilum will obliterate the silhouette of the pulmonary vessels. If the pulmonary vessels can be visualized through the mass it is either a posterior or more commonly an anterior mediastinal mass.
Mediastinal Mass Differential Diagnosis by Compartment:
Anterior:
- Thymic Mass
-Thyroid Mass
-Parathyroid Mass
-Lymphoma
-Germ cell tumors ( Teratoma )
- Mesenchymal mass ( Lipoma , Hemangioma , Leimomyoma )
Middle:
-Lymph nodes
-Foregut and mesothelial cysts (Bronchogenic, Esophageal, Pericardial )
-Tracheal and central bronchial neoplasms
-Diaphragmatic hernias
-Vascular lesions (Aorta, Pulmonary Artery, Azygos , etc.)
Posterior:
-Neurogenic tumors
-Bone Lesion
- Extramedullary hematopoeisis
References:
Camilla RW, et al. A Diagnostic Approach to Mediastinal Abnormalities. RSNA. Radiographics . Vol 27 Iss 3. May-June 2007. http://pubs.rsna.org/doi/full/10.1148/rg.273065136
Goodman LR. Felson’s Principles of Chest Roentgenology , 3rd Ed. December 21, 2006.
(Click for a larger image.)
Original case written by its authors at Virginia Commonwealth University and published at this address as part of a weekly teaching collection. Reproduced here as an archive.