ANTERIOR MEDIASTINAL MASSES

ANTERIOR MEDIASTINAL MASSES:

The anterior mediastinum contains the following structures: thymus, lymph nodes, ascending aorta, pulmonary artery, phrenic nerves and thyroid.
The most common lesions that you will see in the anterior mediastinum will either be of thymic or lymph node origin.Even the germ cell tumors arise from the pluripotent cells of the thymus.Before you want to biopsy an anterior mediastinal mass, do not forget that some of these lesions can be vascular in origin.
The four T's make up the mnemonic for anterior mediastinal masses::
Thymus
Teratoma (germ cell)
Thyroid
Terrible Lymphoma

RADIOLOGY:

1-HILUM OVERLAY SIGN:

On the chest film there is a mass that has obtuse angles with the mediastinum, so it is a mediastinal mass.The hilar vessels are seen through this mass, so it does not arise from the hilum and probably will arise from the anterior mediastinum.The anterior location was confirmed on a CT.Most commonly this will be a mass of thymic or lymphatic origin.This proved to be a lymphoma in a HIV-positive patient.

2-OBLITERATED RETRO-STERNAL SPACE:

On the PA film there is a lobulated widening of the superior mediastinum.On the lateral chest film the retrosternal clear space is obliterated.
This happened to be a patient with lymphoma.

3-FDG STUDY:

FDG-PET images of the same patient.There are multiple lymphatic masses in the anterior, middle and even posterior mediastinum, spreading to the neck.

4-CYSTIC ANTERIOR MEDIASTINAL MASSES:


The anterior mediastinum is an important location for cystic masses. Masses can be entirely cystic (thymic cysts) or have solid components (lymphoma or cystic thymoma). Some masses are cystic with enhancing septations - in these cases you should think of a germ cell tumor.