The document describes a case of a 27-year-old man presenting with chronic dry cough and referred for chest imaging. Chest x-ray revealed a well-defined round radio-opaque lesion in the left perihilar region. Further imaging found the mass to be arising from the left main bronchus in the middle mediastinum. Differential diagnoses included bronchogenic cysts and esophageal duplication cysts. Based on features of a sharply demarcated mass arising from the bronchus, the final diagnosis was determined to be a bronchogenic cyst, a congenital malformation of the bronchial tree.

1. JSS Medical College, Mysuru
CASE OF THE WEEK
DR KAVITHA K.
DR SHIKHAR GARG
(Post Graduate Residents-Radiology)

2. PRESENTING COMPLAINT
27 year old man came with history of chronic
dry cough. No h/o fever, hemoptysis, loss of
weight.
He was referred to the radiology department for
further evaluation.

3. What is the
imaging
modality?
What are your
findings?

4. What is the
imaging
modality?
What are your
findings?
What are your
differential
diagnosis?

5. FINDINGS

6. Chest X-Ray PA
view shows a well
defined round
radio-opaque
lesion in the
left perihilar
region.
CHEST X-RAY -
PA VIEW

7. OBTUSE ANGLE WITH LUNG
Based on the
findings of the
radiograph we
can say that it’s a
medisatinal mass
FINDINGS

8. DIFFERENTIALDIAGNOSIS
The mass seems to be arising
from left main bronchus.

9. LEFT LATERAL
X RAY
Left lateral xray of
the chest showing a
well defined radio-
opaque lesion
middle mediastinum
abutting the left
main bronchus and
carina(arrowhead).

10. SO HOW DO WE DIFFERENTIATE
MEDIASTINAL MASS FROM PARENCHYMAL
MASS?

11. MEDIASTINAL VS PARENCHYMAL MASS
• Unlike lung lesions, a mediastinal mass will not
contain air bronchograms.
• Margins with the lung will be obtuse.
• Will not move with resipration on fluoroscopy.
• Pencil sharp borders.
• Broad based towards the mediastinum.

12. A lung mass abutts the
mediastinal surface
and creates acute
angle with the lung.

13. • A mediastinal mass
will sit under the
surface of the
mediastinum,
creating obtuse
angles with the lung.

14. SUPERIOR
MEDIASTINUM
Above the level
of
the pericardium
and plane of
Ludwig.

15. INFERIOR
MEDIASTINUM
Below the plane of
ludwig

16. Anterior
mediastinum: Anterior to
the pericardium
Middle
mediastinum: Within the
pericardium
Posterior
mediastinum: Posterior
to the pericardium
DIVISIONS OF INFERIOR
MEDIASTINUM

17. Anterior mediastinum
Thymus, lymph nodes
and
retrosternal thyroid
CONTENTS OF INFERIOR
MEDIASTINUM
Middle mediastinum
The heart,
Pericardium, Great
vessels,
Tracheal bifurcation
and both main
bronchi.
Posterior mediastinum
Descending aorta,
Oesophagus, Thoracic
duct, Azygous &
hemiazygous venous
systems.

18. LETS LEARN THE SIGNS WHICH HELP US
TO LOCALISE A MEDIASTINAL MASS ON A
FRONTAL RADIOGRAPH

19. The differential
attenuation of x-ray
photons by two
adjacent structures
defines the
silhouette
SILHOUETTE
SIGN
Loss of right cardiac silhouette due tor right lung middle lobe pneumonia

20. When a mass arises from
the hilum, the pulmonary
vessels are in contact with
the mass and their
silhouette is obliterated.
Visible vessles implies that
the mass is not contacting
the hilum, and is either
anterior or posterior to it.
HILUM OVERLAY
SIGN

21. Helps to distinguish a
bulky hilum due to
pulmonary artery
dilatation from a
mass.
Vessels can be seen to
converge and join a
dilated pulmonary
artery.
HILUM
CONVERGENCE
SIGN
A CASE OF PULMONARY ARTERY
HYPERTENSION

22. A mass in the posterior
mediastinum, is
surrounded by the lung
tissue from all sides.
This leads to a well-
defined cephalic border
seen above the clavicle
CERVICO
THORACIC SIGN
Negative cervico-thoracic
sign- s/o posterior
mediastinal mass
Well defined
borders above
the clavicle

23. ABDOMINO
THORACIC SIGN
A thoracic lesion
which has its
caudal end visible
below the dome
of
diaphragm must be
in the posterior
mediastinum.
Mass Extending below the Diaphragm

24. DIVISIONS ON LATERAL IMAGING

25. DIFFERENTIAL DIAGNOSES OF
MEDIASTINAL MASSES

26. CT AND MRI WILL HELP US TO LOCALIZE,
FURTHER CHARACTERISE VARIOUS
MEDISTINAL MASS AND ALSO HELPS IN
EVALUTING INVASION INTO ADJACENT
STRUCTURES.
FURTHER IMAGING

27. Final conclusion: Well demarcated radio-opaque mass in
the middle mediastinum arising from the left main
bronchus.

28. BASED ON THE XRAY FINDINGS
DIFFERENTIALS –
Oesophageal duplication cysts - Thick walled cysts
found adjacent to the oesophagus
Bronchogenic Duplication cysts - Sharply demarcated
round/ oval thin walled mass filled with proteinacious
fluid usually in the medial 1/3 of lungs arising from the
bronchus.

29. FINAL DIAGNOSIS
BRONCHOGENIC CYST

30. BRONCHOGENIC CYST
Bronchogenic cysts are congenital malformations of the bronchial tree.
They can present as a mediastinal mass that may enlarge and cause local
compression.
It is also considered the commonest of foregut duplication cysts.

31. Bronchogenic cysts are asymptomatic and are found
incidentally.
When large, mass effect may result in bronchial
obstruction leading to air trapping and respiratory
distress.
CLINICAL PRESENTATION

32. Sharply demarcated round mass in the medial 1/3 of
lungs.
They do not communicate with the bronchial tree, and
are therefore not air filled.
They contain fluid ,variable amounts of proteinaceous
material, blood products, and calcium oxalate .
It is the latter three components that result in
increased attenuation mimicking solid lesions.
FEATURES

33. CT findings
Well circumscribed
spherical mass of
variable
attenuation with
variable fluid
composition explaining
the different CT
attenuations observed.
The degree of CT
attenuation often
depends on the amount
of internal proteinaceous
content .
FURTHER IMAGING

34. MRI
T2WI
High signal intensity
due to fluid content