a goitre with a portion of its mass located in the
mediastinum
Primary intra-thoracic goitres arise from aberrant thyroid
tissue which is ectopically located in the mediastinum,
receive their blood supply from mediastinal vessels and are
not connected to the cervical thyroid. They are rare,
representing less than 1% of all RGs
Secondary RGs develop from the thyroid located in its
normal cervical site. Downward migration of the thyroid
into the mediastinum is facilitated by negative intra-thoracic
pressure, gravity, traction forces during swallowing and the
presence of anatomical barriers preventing the enlargement
in other directions (thyroid cartilage, vertebral bodies, strap
muscles, especially in patients with a short, large neck).
These secondary RGs are, characteristically, in continuity
with the cervical portion of the gland and receive their
blood supply, depending on cervical vessels, almost always
through branches of the inferior thyroid artery.
Plunging goiter : rise with deglutition and then
descent again through the thoracic inlet
Mediastinal goiter : lie wholly in the chest but
are connected with the thyroid and supplied by
thyroid vessels through narrow band
Intrathracic goiter : lie wholly in the chest but
completely separated from the gland supplied
by mediastinal vessels
Short-necked individuals
Usually after middle age
Intrathracic goiter more common in men
May remain symptomless for years
Dyspnea due to displacing and compressing on
the trachea
The Dyspnea aggravated by any posture that
reduces the thoracic inlet as lying down or
flexion the neck
The patient prefer to spend the night in a chair
Some time they miss diagnosed as asthmatic
Sometimes there is dysphagia
Inspection
Palpation : thyroid gland enlarged
Percussion of the sternum may reveal
retrosternal dullness
X-ray
X-ray
CT
CT
CT
Tc
99m
Fiberscope
Thyroidectomy is the only line of treatment
Mostly via cervical approach , rarely a median
sternotmy is required
Devascularization is done via the neck from
which the retrosternal portion derived its blood
supply
Special care should be exerted to avoid injury
of the recurrent laryngeal nerves during the
delivery of retrosternal goter