mediastinal mass
TRANSCRIPT
JSS Medical College, Mysuru
CASE OF THE WEEK
DR KAVITHA K.DR SHIKHAR GARG
(Post Graduate Residents-Radiology)
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.
What is the imaging modality?
What are your findings?
What is the imaging modality?
What are your findings?
What are your differential diagnosis?
FINDINGS
Chest X-Ray PA view shows a well defined round radio-opaque lesion in theleft perihilar region.
CHEST X-RAY - PA VIEW
SHARP BORDERS
OBTUSE ANGLE WITH LUNG
NO AIR BRONCHOGRAMS
Based on the findings of the radiograph we can say that it’s a medisatinal mass NO SILHOUETTING OF LEFT HEART BORDER
FINDINGS
DIFFERENTIAL DIAGNOSIS
The mass seems to be arising from left main bronchus.
LEFT LATERALX RAYLeft lateral xray of the chest showing a well defined radio-opaque lesion middle mediastinum abutting the left main bronchus and carina(arrowhead).
SO HOW DO WE DIFFERENTIATE MEDIASTINAL MASS FROM
PARENCHYMAL MASS?
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.
A lung mass abutts the mediastinal surface and creates acute angle with the lung.
• A mediastinal mass will sit under the surface of the mediastinum, creating obtuse angles with the lung.
SUPERIOR MEDIASTINUM
Above the level of the pericardium and plane of Ludwig.
INFERIORMEDIASTINUM
Below the plane of ludwig
Anterior mediastinum: Anterior to the pericardium
Middle mediastinum: Within the pericardium
Posterior mediastinum: Posterior to the pericardium
DIVISIONS OF INFERIOR MEDIASTINUM
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.
LETS LEARN THE SIGNS WHICH HELP US TO LOCALISE A MEDIASTINAL MASS ON A FRONTAL RADIOGRAPH
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
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
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
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
CERVICOTHORACIC SIGN
Negative cervico-thoracic sign- s/o posterior mediastinal mass
Well defined borders above the clavicle
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
DIVISIONS ON LATERAL IMAGING
DIFFERENTIAL DIAGNOSES OF MEDIASTINAL MASSES
CT AND MRI WILL HELP US TO LOCALIZE, FURTHER CHARACTERISE VARIOUS MEDISTINAL MASS AND ALSO HELPS IN EVALUTING INVASION INTO ADJACENT STRUCTURES.
FURTHER IMAGING
Final conclusion: Well demarcated radio-opaque mass in the middle mediastinum arising from the left main bronchus.
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.
FINAL DIAGNOSIS
BRONCHOGENIC CYST
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.
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
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
CT findingsWell 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 .
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FURTHER IMAGING
MRI
T2WI High signal intensity due to fluid content