This document contains descriptions and CT scan images of various middle mediastinal lesions that can be identified on computed tomography scans. It includes examples of mediastinal lipomatosis, epicardial fat pads, pericardial cysts, bronchogenic cysts, lymphadenopathy, bronchogenic carcinoma, lymphoma, sarcoidosis, ectopic parathyroid adenoma, fibrosing mediastinitis, aneurysms of the subclavian artery and aorta, and vascular anomalies such as a right-sided aortic arch, left-sided superior vena cava, and azygos continuation of the inferior vena cava. Each image shows characteristics of a different mediastinal pathology visible on CT.

1. 26Middle Mediastinal Lesions on
Computed Tomography

2. CLINICAL IMAGAGING
AN ATLAS OF DIFFERENTIAL DAIGNOSIS
EISENBERG
DR. Muhammad Bin Zulfiqar
PGR-FCPS III SIMS/SHL

3. • Fig C 26-1 Mediastinal lipomatosis. Diffuse
fatty lesion with a mass effect on the superior
vena cava and azygos vein.54

4. • Fig C 26-2 Epicardial fat pad. Homogeneous fat
attenuation (arrow) adjacent to the right
border of the heart.52

5. • Fig C 26-3 Pericardial cyst. Contrast CT scan
shows a thin-walled cyst of water attenuation
(arrow).55

6. • Fig C 26-4 Bronchogenic cyst. CT scan in a young
man with an incidental upper respiratory
infection shows a large right upper mediastinal
mass extending from the right of the trachea to
the posterior chest wall. The cyst had a uniform
appearance and near-water density and extended
vertically from the lower pole of the thyroid gland
to the carina.56

7. • Fig C 26-5 Lymphadenopathy. The enlarged nodes
(arrow) obliterate the air-soft tissue interface
between the right lung and the tracheal wall
(right paratracheal stripe).52

8. • Fig C 26-6 Bronchogenic carcinoma. Soft-tissue mass
within the aortopulmonary window and subcarinal
space, a finding consistent with metastatic
lymphadenopathy. There is also lymphadenopathy in
the paratracheal region, which produced a thickened
right paratracheal stripe on plain radiographs.57

9. • Fig C 26-7 Lymphoma. Enlarged nodes (arrow)
obliterate the normal concave border of the
interface between the left lung and the
mediastinum constituting the
aorticopulmonary window.52

10. • Fig C 26-8 Sarcoidosis. Diffuse bilateral
mediastinal and hilar adenopathy. Calcification in
the affected hilar nodes suggests a prolonged
clinical course. Note the simultaneous presence
of huge subcarinal nodes (arrowheads), an
unusual finding in other granulomatous diseases
such as tuberculosis.58

11. Fig C 26-9 Ectopic parathyroid adenoma. Large right paratracheal mass
(arrow) with diffuse osteopenia from primary hyperparathyroidism.57

12. • Fig C 26-10 Fibrosing mediastinitis. Soft-tissue mass
diffusely infiltrates the mediastinum. There is a
subcarinal mass (M), encasement of the left main
coronary artery (arrow), and narrowing of the left
superior pulmonary vein (S). (A, ascending aorta; D,
descending aorta; P, main pulmonary artery.)55

13. • Fig C 26-11 Aneurysm of the left subclavian
artery. Contrast-enhanced scan shows the
large aneurysm partially filled with thrombus
(t).43

14. • Fig C 26-12 Chronic traumatic aortic aneurysm. CT scans through (A)
and slightly below (B) the aortic arch after the intravenous injection
of contrast material demonstrate calcification in the wall of the
aneurysm (arrowheads) and a large filling defect consisting of
thrombus (arrow).

15. • Fig C 26-13 Right-sided aortic arch. This vascular
structure (arrow) caused loss of the normal right
paratracheal stripe on plain radiographs.52

16. • Fig C 26-14 Left-sided superior vena cava. CT
scan at the level of the aortic arch shows the
anomalous vessel (arrow), which drains into
the coronary sinus.52

17. • Fig C 26-15 Azygos continuation of the inferior
vena cava. Enlargement of the azygos vein
(arrow) that widened the inferior margin of
the right paratracheal stripe on plain
radiographs.52