This document provides an overview of substernal goiters, which are enlarged thyroid glands that extend below the sternum. It defines substernal goiters and classifies them based on the percentage of the mass in the neck or chest. The document discusses the pathogenesis, clinical presentation, investigations including imaging studies, and management including thyroid suppression, radioiodine therapy, and surgical approaches. Surgery remains the primary treatment and can involve cervical, partial sternotomy, thoracotomy, or combined approaches depending on the extent of the mediastinal extension. Postoperative monitoring and potential complications are also outlined.

1. WELCOME TO
BENAAM TUBE

2. By Dr Mengistu Kassa
Assistant professor of General surgery
Debretabor university , Ethiopia

3. Outlines
• Introduction
• Definition
• classification
• Pathogenesis
• Presentation
• Management
• References

4. Introduction
• Goiter is enlargement of the thyroid gland
associated with a thyroid gland that is
functioning properly or not
• Defination of substernal goiter is variable
• Account less than 10% of all goiters and 5% to
6% of apparent mediastinal masses
• The management of mediastinal goiters is
challanging because of the complexity of
surgical procedures and associated risks

5. Principle of most
• Almost all arise from cervical thyroid
• Most are symptomatic
• Almost all are pathologically benign
• Most are euthyroid
• Most are adequately diagnosed and evaluated by
CT.
• Almost all can be removed transcervically.
• Most are anterior or lateral to the trachea
• Most of pts experience an improvement in
symptoms after surgery .
•

6. Definition
• The definition of a substernal goiter in less clear
• Various definitions have been proposed
A substernal goiter has been variously defined
as an enlarged gland
• With some portion remained permanently
retrosternal(Kocher).
• With its lower position remaining below the
sternal notch with the neck
hyperextended(Torre)

7. With extension down to the aortic arch(Crile’s)
With its lower border reaching the transverse
process of T4 vertebrae or below(Linskog’s)
With greater than 50% of the great volume
presenting behind the sternum(Katlic)
When It requires mediastinal exploration and
dissection for removal(Lahey)
When the intrathoracic component appears to
extend more than 3cm from the thoracic
inlet(Escharpase)

8. Classification
• Several authors have attempted to offer various
classifications schemes for substernal goiter to
objectively describe the degree of substernal
extension
• Lahey classification according to the relationship
to the aortic arch
Grade 1- includes those extending nearly to the
arch of aorta
Grade 2- includes those extending to arch of
aorta or beyond

9. .....
Higgins, in 1927, classified these goiters based
on relative percentage of the mass in the neck
or chest:
1. More than 50% in neck, substernal;
2. more than 50% in chest, partially
intrathoracic; and
3. more than 80% in chest, completely
intrathoracic

10. …
• Cohen and cho graded substernal goiters
according to the percentage of the
intrathoracic component of the goiter
• Grade 1: 0-25%
• Grade 2: 26-50%
• Grade 3: 51-75%
• Grade 4: >75%

11. Pathogenesis
• Over 98% of substernal goiter derived from a
caudal migration of cervical goiters.
• Tends to migrate anterior to the trachea,
esophagus, RLN, subclavian vessels in 85-90% of
cases and to posterior mediastinum in 10%–
15%
• Contributing factors : negative intrathoracic
pressure, effect of gravity, large potential space

12. • Several theories of pathogenesis includes;
Develop from thyrothymic congenital rests in
the thyrothymic ligament… appear after surgery
Embryological hyperdescent of thyroid tissue
It may Start as exophytic nodule from thyroid
inferior pole and over time there is attenuation
of nodule-thyroid stalk

13. Primary mediastinal goiter
• The category of truly isolated mediastinal
tumors is controversial.
Terms used to describe this situation have
included;
isolated
ectopic
heterotopic, and
aberrant mediastinal/intrathoracic goiter

14. Ectopic thyroid has been reported
I. At the aortic root,
II. in the pericardium, and
III. within cardiac muscle or esophageal wall

15. Diagnostic criteria
• Completely separated from the gland in the
neck,
• Thoracic blood supply
• Normal or completely absent Cx thyroid
• No prior thyroid surgery
• No current or previous invasive thyroid
malignancy,
• No similar pathologic process in cervical and
so-called ectopic thyroid tissue

16. Clinical presentation
• More frequently in the fifth or sixth decades
• Thirty to forty percent are asymptomatic
• In about 20% no palpable neck mass
• 10% to 20% of patients may have prior history
of surgery
Upper airway obstruction can occur acutely

17. In Symptomatic cases
• The rates for symptoms are;
 cough, dyspnea, positional or nocturnal
breathing difficulty (35% to 96% of patients;
dysphagia in 18% to 60%, and
hoarseness in 10% to 26%
venous obstruction(~10%)

18. Investigation
• FNAC &TFT
• Chest or Neck x-ray
• U/S
• CT scan
• MRI
• Indirect laryngoscope

19. Ultrasonography FNAC & TFT
• Undertaken only if concern
of poorly differentiated
carcinoma and toxic nodule
exists
• Bony thorax limits visibility
• It can help to;
 define the cervical extent
of disease
 Assess parenchymal lesion

20. Chest or Neck x-ray
• Provides the first
evidence of a
mediastinal mass
• Overall correlation
between imaging studies
and symptoms of
substernal goiter is poor
• Can suggest substernal
thyroid masses in 60% to
90% of cases

21. CT scan
• A cross-sectional
imaging study with CT
or MRI provides the
most important
information for the
evaluation and planning
the surgical
approach to substernal
goiters

22. • CT of the chest with
mediastinal goiter that
originates in the Rt lobe of
the thyroid and extends
down into the mediastinum
• It is heterogeneous and
enhancing.

23. Magnetic Resonance Imaging
• It provides excellent
information on
relationships to the
great vessels and
• it is superior at
detecting tracheal or
esophageal invasion

24. Indirect Laryngoscopy
• Absolutely indicated if there is any history of
hoarseness or concern for cord function
• At the time of surgery to see the condition of
the vocal cords and position of the larynx
• Post operatively to review cord function

25. Management
• Thyroid Suppression
• Radioiodine Therapy
• Surgery

26. Thyroid Suppression
• Attempted suppression with thyroxine is
generally ineffective and inappropriate,
• The effect is modest, delayed, unpredictable
and not durable

27. Radioiodine Therapy
• Might be necessary only when surgery is
precluded
• The full effect of radioiodine treatment is
unpredictable and often not evident for 3 to 6
months
• Complications
• Thyroiditis (∼5%),
• Need for second treatment (∼20%),
• Hypothyroidism (60%-100%)
• Radiation-induced Graves’ disease (∼10%)

28. Surgery
• The diagnosis of substernal goiter is an absolute
indication
• Remain a great challenge to the operating
surgeon
• Distorted neck base anatomy, restricted surgical
access of the thoracic inlet, mediastinal
extension, increased size of the thyroid gland,
increase glandular vascularity has increased skill
demand

29. Surgical Intervention
• The extent of surgery can be;
 bilateral total or near-total thyroidectomy…
the lowest recurrence rate
or
unilateral surgery is an acceptable if
substernal goiter could arise clearly from just
one thyroid lobe…. a higher recurrence rate

30. Surgical exposures
Cervical- Nearly all (97%-99%) mediastinal
goiters
A partial upper sternotomy
Combining anterior thoracic and
transclavicular
video-assisted exposure with cervical
exposure
simultaneously combine cervical and
posterolateral thoracotomy approaches

31. Postoperative
• Oral thyroxine replacement
• Oral calcium carbonate supplementation until
calcium status is known

32. Complications
• RLN injury
• Hypoparathyroidism
• Tracheomalacia
• Mediastinal
hematoma and
embolism, chyle
fistula, and pleural
effusion
• Tracheostomy
• Bleeding
• Pneumothorax
• Wound infection
• Esophageal injury
• Horner’s sysyndrom
• Recurrence

33. Recurrence
• Highly dependent on the extent surgery
• Can manifest after as long as 10 to 30
years
• Long-term studies report recurrence rates
of 15% to 60%
• More common in young females with a
family history of this diagnosis
• Treatment : radioactive iodine

34. References
• Endocrine Surgery 2nd ed
• Shield's thoracic surgery
• Pearson's Thoracic surgery
• Adult chest surgery

35. Thank you
.