Archived case 193 · January 14-January 21, 2016
52-year-old female, presents with left neck and shoulder pain
What is the abnormality and where would you localize it? 2. What is your differential diagnosis? 3. What would be the next step?
Radiologic Findings: PA and lateral chest radiographs demonstrate thickening of the right paratracheal stripe and abnormal contour of the right upper right mediastinum with a convex density obscuring the mediastinal border. The spine is well visualized. The airway is patent, however the trachea appears mildly displaced towards the left. On the lateral view, there is also a convex density projecting in the retrotracheal triangle (Reider triangle). The retrosternal space demonstrates diffusely mildly increased density, however without definitive lesion and this may be contributed to mediastinal fat. The retrocardiac space is clear. Axial, coronal and sagittal CT images of the chest show a low attenuation lesion in the right upper and lower paratracheal region. This lesion is homogenous in attenuation, well defined, without internal enahancement or septation, and appears pliable. There is no evidence of invasion of the adjacent structures or surrounding soft tissue stranding. All these findings are most consistent with a cystic structure. The measured density of this lesion was 12-18 Hounsfield units consistent with fluid containing proteinaceous material. Answer Diagnosis: Pericardial cyst (pathology proven)
Pericardial cyst (pathology proven)
Answer
Diagnosis: Pericardial cyst (pathology proven)
Differential Diagnosis for CT findings:
1. Foregut cyst (bronchogenic versus esophageal duplication)
2. Pericardial cyst
Differential diagnosis for radiographic findings would be broad and include also
3. Lymphadenopathy
4. Neoplasm
5. Thyroid goiter
Discussion
Mediastinal masses in the paratracheal space typically manifest radiographically as a contour abnormality or an area of increased opacity. Computed tomography or magnetic resonance imaging is usually required for diagnosis.
Cystic mediastinal lesions include a foregut cyst (bronchogenic, esophageal duplication, neurenteric), pericardial cyst, thymic cyst, and vascular malformations. Some additional lesions may have cystic appearance, including meningocele, vascular malformations, schwannoma, mature teratoma, abscess, and low attenuation lymph node.
The CT features of benign mediastinal cyst are: well-defined contour, thin wall, homogeneous low usually (0–20 HU) without internal septation, lack of post contrast enhancement, no evidence of invasion of the adjacent structures.
Pericardial cysts are uncommon congenital cysts of the anterior and middle mediastinum. Rarely can they occur as a result of previous pericarditis. Most cases are diagnosed incidentally on imaging and remain asymptomatic. They are typically located in the right cardiophrenic angle, but can be found anywhere adjacent to the heart/pericardium as high as at the level of the aortic arch.
Selected Readings:
1. Whitten CR, Khan S, Munneke GJ, Grubnic S. A Diagnostic Approach to Mediastinal Abnormalities. RadioGraphics 2007 27:3, 657-671
2. Parker MS, Rosado de-Christenson ML, Abbott GF. Congenital Cysts: Bronchogenic cyst . In: Chest Imaging Case Atlas , 2nd edition. T hieme New York 2012; 663-668.
3. Brown LR, Aughenbaugh GL. Masses of the anterior mediastinum: CT and MR imaging. American Journal of Roentgenology 1991 157:6, 1171-1180
4. Suut S, Al-Ani Z, Allen C, Rajiah P, De, AL-Harbi A, AL-Jahdali H, Khan AN. Pictorial essay of radiological features of benign intrathoracic masses. Ann Thorac Med. 2015 Oct-Dec;10(4):231-42
5. Jeung MY, Gasser B, Gangi A, Bogorin A, Charneau D, Wihlm JM, et al. Imaging of cystic masses of the mediastinum. Radiographics 2002;22 Spec No:S79-93.
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.