Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_623_Библиотеки_им_академика_М_И_Перельмана
.pdf
The thyroid 395
https://t.me/medicina_free
response to the level of thyroid hormones in the blood
by a negative feedback mechanism. The secretion of
TSH is also under the influence of the hypothalamic
thyrotrophin-
releasing hormone (TRH).
Pharmacological control
ofsecretion
The production of thyroid hormones can be inhibited
by thionamide antithyroid drugs such as carbimazole, propylthiouracil and methimazole which block
the binding of iodine but do not interfere with the
uptake of iodide by the gland.
High doses of iodine (e.g. Lugol’s
patients with excessive thyroid hormone production result in an increase in the amount of iodinerich colloid, and a diminished liberation of thyroid
hormones; the gland also becomes less vascular.
The effects of iodide treatment are maximal after
2 weeks of treatment and then diminish. This
canbe useful in preparing hyperthyroid patients
for surgery when antithyroid drugs have been
ineffective.
Lack of iodine in the diet prevents the formation of
thyroid hormones, and excess pituitary TSH is produced, which may result in an iodine- deficient goitre.
Thiocyanates prevent the thyroid gland from taking
up iodide.
2
) given to
which may replicate even in the absence of TSH. The
difference in areas of excessive activity and other
areas of regression results in a varied appearance of
the gland. Some follicles are lined with hyperactive
epithelium and others with flattened atrophic cells.
Some contain no colloid, others an excessive amount.
The thyroid interstitium is excessive, with some
fibrosis and mononuclear cell infiltration. Factors
which are associated with the development of a multinodular goitre include female gender and elevated
TSH secondary to iodine deficiency or natural goitrogens. Nodular goitres may produce a normal amount
of T4, but sometimes excessive T4 production results
in hyperthyroidism in this condition (toxic nodular
goitre). Radioactive iodine- 131 is the treatment of
choice in such cases.
The thyroid is usually enlarged, irregular and
nodular and, although one lobe often predominates
at presentation, the condition does affect the entire
gland.
Symptoms
The enlarging thyroid can produce a number of ‘pressure’ symptoms including dysphagia, breathlessness,
orthopnoea, hoarseness and facial swelling.
Investigation ofmultinodular
goitre
Pathology ofgoitre
The term ‘goitre’ is used to describe any enlargement
of the thyroid gland irrespective of the underlying
pathology. It can be diffuse or nodular and nonor toxic.
Multinodular goitre
The aetiology of multinodular goitre is unclear but
several contributing factors have been identified. The
principal cause is believed to be a functional heterogeneity of follicular cells, with some having a higher
growth potential than normal follicular cells, some of
2
Jean Guillaume Auguste Lugol (1788–1851), Physician,
Hôpital Saint- Louis, Paris. He proposed a solution of iodine
as a treatment for tuberculosis, for which it was ineective.
Its use in treating thyrotoxicosis was pioneered by Henry
Stanley Plummer (1874–1936).
toxic
Patients require a few specific investigations.
•
TSH concentration is low in the few patients with
hyperthyroidism in association with multinodular
goitre.
•
Ultrasound of the gland to exclude any suspicious
nodules.
• Computed tomography (CT) of the neck and
thoracic inlet may be required to define the size of
the goitre, the extent of the goitre including any
retrosternal extension, and to identify the
of tracheal compression (Box39.1).
presence
Complications
• Tracheal displacement or compression.
• Haemorrhage into a cyst, producing pain and
increased swelling (which may produce sudden
tracheal compression).
• Toxic change.
• Malignant change (rare).
396 The thyroid
https://t.me/medicina_free
Box 39.1 Symptoms ofmultinodular goitre
•
Dysphagia: usually of solids, worse with certain
food, for example meat.
•
Breathlessness: worse on exertion, bending
forward (especially, retrosternal extension).
•
Orthopnoea: owing to the weight of the gland
pressing on the trachea when lying flat.
•
Stridor: from significant tracheal compression.
•
Hoarseness: from pressure on one recurrent
laryngeal nerve (rare).
•
Facial congestion: venous engorgement especially
on raising arms (Pemberton’s sign
3
).
Clinical features
inthyroid disease
Patients may present complaining of a lump in the
neck and/or with symptoms due to excessive or
diminished amounts of circulating thyroxine.
The thyroid swelling
The characteristics of an enlarged thyroid are a mass
in the neck on one or both sides of the trachea, which
moves on swallowing, since it is attached to the larynx
by the pretracheal fascia.
Colloid goitre
All diseases of the thyroid are more common in geographical locations in which the water and diet are
low in iodine. In the UK, the most notorious district
historically was Derbyshire, and the frequency of goitres in this region gave rise to the term ‘Derbyshire
neck’. Iodination of table salt has all but abolished this
state of affairs. Switzerland, Nepal, Ethiopia and Peru
are also areas where natural iodine is very scarce in
the diet and water, and thyroid disease is more common. The most common lesion of the thyroid gland
due to iodine deficiency is the colloid goitre, in which
the gland is enlarged and the acini are atrophic with a
large amount of colloid. This can also occur in physiological goitres (pregnancy and puberty). This accumulation of colloid is probably due to over secretion
of TSH from the anterior pituitary, acting on the thyroid, which is unable to produce T4.
Hyperplasia
In primary hyperthyroidism (Graves’ disease4), the
thyroid is uniformly enlarged and there is hyperactivity of the acinar cells with reduplication and infolding
of the epithelium. The gland is very vascular and
there is little colloid to be seen. Lymphocyte infiltration is usually a predominant feature.
Retrosternal goitre
Evidence of retrosternal enlargement of the thyroid
should be sought by palpation and percussion with
the neck fully extended. A retrosternal thyroid can
block the venous return to the superior vena cava and
result in engorgement of the jugular veins and their
tributaries and in oedema of the upper part of the
body– a cause of the superior mediastinal syndrome.
In such cases, CT imaging of the thoracic inlet should
be performed to assess its extent.
Tracheal displacement
The trachea should be examined to determine displacement or compression by the thyroid enlargement; the patient should be asked to take a deep breath
with the mouth open, when stridor may become
apparent.
Vocal cord integrity
The vocal cords should be examined by flexible
nasendoscopy or indirect laryngoscopy, as thyroid
carcinoma may infiltrate the recurrent laryngeal
nerves and cause vocal cord paralysis. If surgery is
contemplated, it is important to know whether or not
the cords are functioning normally before operation.
3
Hugh Spear Pemberton (1890–1956), Physician, Liverpool,
UK.
4
Robert Graves (1796–1853), Physician, Meath Hospital,
Dublin, Ireland.
Regional nodes
As with any other lump, the regional lymph nodes
must be examined in any case of thyroid swelling. The
draining nodes of the thyroid lie along the carotid
The thyroid 397
https://t.me/medicina_free
sheath on each side. Hard enlarged nodes strongly
suggest malignant disease of the thyroid.
The physiological state ofthe
patient
Determine whether the patient is euthyroid, hyperthyroid or hypothyroid. In the majority of patients,
this can be determined from the clinical features.
Hyperthyroidism
Clinical features of hyperthyroidism are determined by
examination of the eyes and the hands, as well as from
the history and examination of the neck. Thyroxine
potentiates the actions of adrenaline (epinephrine),
and many of the features of hyperthyroidism represent
increased activity of the sympathetic nervous system.
History
The patient is irritable and nervous, and cannot keep
still. The appetite is increased and yet there is loss of
weight; diabetes mellitus is the other condition in
which this paradox occurs. Diarrhoea is occasionally
a feature. The patient prefers cold environments
rather than warm. Palpitations due to tachycardia or
atrial fibrillation may occur.
Examination
The thyroid gland
The thyroid itself is usually smoothly enlarged but not
invariably so. It may be highly vascular and demonstrate a bruit and thrill.
Eye signs
• Exophthalmos is present in most patients with
hyperthyroidism of Graves’ disease, owing to
oedema and infiltration by mononuclear cells of
the orbital fat and extrinsic muscles of the eye.
• Lid retraction: the innervation of the levator palpebrae superioris is partly under sympathetic
control. In hyperthyroidism, it is tonically active,
retracting the upper lid, giving the appearance
that the patient is staring.
• Lid lag: ask the patient to follow your finger as you
move it from over the head downwards – the
upper lid does not immediately drop, revealing
the white sclera above the cornea.
•
Dilated pupils owing to increased sympathetic
pupil dilator tone.
Double vision following the examiner’s finger to
•
the upper outer quadrant. This is due to infiltration of the extrinsic muscles of the eye, which
causes exophthalmic ophthalmoplegia.
Exophthalmos is an extremely distressing condition for the patient and, if severe, the patient is unable
to close the eyelids; the eyes are then susceptible to
corneal ulceration and eventual blindness. This
condition is difficult to treat, but may respond to highdosage corticosteroids; surgical decompression of the
orbit with suture of the eyelids across the eyeball
(tarsorrhaphy) may be required.
The hands
• Sweating: the hands are warm and moist.
• Tachycardia: a rapid pulse is almost invariable
and typically the sleeping pulse is also raised.
There may be atrial fibrillation and indeed the
patient may present with heart failure. A rapid
sleeping pulse rate permits differentiation of
hyperthyroidism from an acute anxiety state; such
patients when sleeping will have a normal pulse
rate whereas, in patients with hyperthyroidism,
the sleeping pulse rate will remain elevated.
• Fine tremor of the outstretched hands is present
and reflects the increased sympathetic activity.
•
Finger clubbing, more accurately termed ‘thyroid
acropachy’.
Onycholysis: the nail lifts off the nail bed, a condi-
•
tion also seen in psoriasis and with some fungal
infections.
•
Pretibial myxoedema, thickening of the subcuta-
neous tissues in front of the tibia, is a rare feature.
Aetiology
Patients with hyperthyroidism fall into two groups:
primary (Graves’ disease) and secondary.
Primary hyperthyroidism (Graves’
disease)
This occurs usually in young women with no preceding
history of goitre. The gland is smoothly enlarged and
exophthalmos common. Symptoms are primarily
398 The thyroid
https://t.me/medicina_free
those of irritability and tremor; exophthalmos and
ophthalmoplegia are often quite marked. Primary
hyperthyroidism is due to the action of autoanti
which bind to, and stimulate, the TSH receptor.
These thyroidlonged stimulatory effect compared with TSH; hence
the traditional name of ‘longstimulators’.
stimulating antibodies have a pro-
acting thyroid
Secondary hyperthyroidism
Secondary hyperthyroidism is overactivity developing in an already diseased and hyperplastic gland. It is
a disease of middle age, occurring in patients with a
existing non- toxic (euthyroid) goitre. The gland is
prenodular and there are no eye changes. Symptoms fall
more on the cardiovascular system, the patient often
presenting in heart failure with atrial fibrillation,
although nervousness, irritability and tremor may
also be present.
bodies
Hashimoto’s disease
Hashimoto’s disease5 is an uncommon thyroid disease
that was the first of the autoimmune diseases to be
elucidated. The patient is usually a middlewoman with clinical evidence of hypothyroidism. The
gland is uniformly enlarged and firm, although it may
occasionally be asymmetrical and irregular.
Macroscopically, its cut surface is lobulated and
greyish yellow. Microscopically, there is diffuse infiltration with lymphocytes, increased fibrous tissue
and diminished colloid. It is an autoimmune disease
in which the patient has developed both a humoral
and cellwithin their own thyroid. Thyroglobulin and microsomal antibodies can be demonstrated in about 90%
of patients.
by demonstrating the presence of thyroid antibodies
and, if necessary, by biopsy, because thyroidectomy
will precipitate severe hypothyroidism in these cases.
Occasionally, lymphoma occurs in such glands.
mediated autoimmune reaction to elements
It is important to diagnose the condition correctly
aged
Hypothyroidism
Congenital hypothyroidism
Congenital hypothyroidism (or cretinism) is a condition in which the child is born with little or no functioning thyroid. The infant is stunted and mentally
subnormal, with puffy lips, a large tongue and protuberant abdomen, often surmounted by an umbilical
hernia.
Adult hypothyroidism
In adults, hypothyroidism (or myxoedema) usually
affects women, and most often occurs in the middle
aged or elderly. These patients have a slow, deep
voice and are usually overweight and apathetic, with
dry, coarse skin and thin hair, especially in the lateral third of the eyebrows. In contrast with hyperthyroidism, myxoedematous patients usually feel cold
in hot weather, have a bradycardia and are constipated. They are often anaemic and may suffer from
heart failure owing to myxoedematous infiltration of
the heart.
Treatment
Thyroxine replacement therapy with levothyroxine
will shrink the gland and treat the symptoms of
myxoedema.
Riedel’s thyroiditis
Riedel’s thyroiditis6 is an extremely rare disease of the
thyroid in which the gland may be only slightly
enlarged, but is woody hard with infiltration of adjacent tissues. It is a chronic inflammatory condition
that is associated with elevated IgG4levels and IgG4positive plasma cell infiltrates, supporting an autoimmune aetiology.
It may be mistaken clinically for a thyroid carcinoma due to its hard texture and apparent infiltration
of the neighbouring muscles, but histologically the
5
Hakaru Hashimoto (1881–1934), Surgeon, Kyushu
University, Kyushu, Japan.
6
Bernhard Riedel (1846–1916), Professor of Surgery, Jena,
Germany.
The thyroid 399
https://t.me/medicina_free
Box 39.2 IgG4- related diseases
The following conditions are increasingly being
recognized to be part of a spectrum of conditions
associated with elevated IgG4levels and plasma
cell infiltrates.
•
Riedel’s thyroiditis.
•
Mikulicz syndrome
glands).
•
Mediastinal fibrosis.
•
Retroperitoneal fibrosis.
•
Peri- aortitis and peri- arteritis.
•
Inflammatory aortic aneurysm.
gland is replaced by fibrous tissue containing a dense
lymphoplasmacytic infiltrate. It is associated with
other IgG4-
Treatment with high- dose steroids may be effective,
but resection of a portion of the gland may be required
if symptoms of tracheal compression develop.
related conditions (Box39.2).
7
(affecting salivary and lacrimal
De Quervain’s thyroiditis
De Quervain’s thyroiditis8 is a rare condition usually
affecting young women. It often follows a viral infection of the upper respiratory tract. The gland is slightly
enlarged, firm and tender. It is generally selfand rarely leads to hypothyroidism.
limiting,
Investigations inthyroid
disease
• Serum free T4 and free T3. Measurement of the bio-
logically active unbound fraction is more accurate
than measurement of total T3 and T4; elevation
suggests hyperthyroidism.
7
Jan Mikulicz- Radecki (1850–1905). Professor of Surgery in
Krakow and Königsberg.
8
Fritz de Quervain (1868–1940), Professor of Surgery, Bern,
Switzerland.
• TSH concentration: raised in myxoedema; suppress ed
in hyperthyroidism, in which the gland secretes T4
autonomously.
•
Thyroid scintigram: radioiodine studies of the
thyroid gland can provide very useful information.
A small tracer dose of γinjected intravenously and the gland scanned with
ray detector to map areas of high uptake
a γreflecting high activity. A nodule in the thyroid
gland that is hyperactive can be pinpointed by this
method, a so nodule that is not producing T4will not take up
the radioiodine, for example a cyst or tumour
(‘cold nodule’).
•
Thyroid antibodies, anti- thyroglobulin antibodies
or antithyroid peroxidase antibodies, indicate
an autoimmune pathology such as Hashimoto’s
thyroiditis, or primary hyperthyroidism; other
autoantibodies are often present.
• Ultrasound of the thyroid gives valuable information as to whether a mass is solid or cystic, unifocal
or multifocal. Certain radiological features can be
markers of increased risk for malignancy and there
are now grading systems to aid the identification of
nodules which should have a needle biopsy.
Fine- needle aspiration and core biopsy allow
•
material to be obtained for cytological and histological examination. It is now the principal investigation for all solitary nodules, often under
ultrasound guidance.
•
Serum cholesterol is usually raised in myxo-
edema and may be normal or a little low in
hyperthyroidism.
Electrocardiogram (ECG): in myxoedema, cardiac
•
involvement will show low electrical activity with
small complexes. Atrial fibrillation complicating
hyperthyroidism will be confirmed.
• CT scan: allows definition of size and extent of goitre, particularly any retrosternal extension and the
presence of tracheal compression.
called ‘hot nodule’. Similarly, a
ray- emitting iodine- 131 is
Clinical classification
ofthyroid swellings
The clinical assessment of a patient with a thyroid
swelling has two components.
400 The thyroid
https://t.me/medicina_free
1 The physical characteristics of the gland itself. Is it
smoothly enlarged? Is there a single nodule
present? Is it multinodular?
2
The endocrine state of the patient. Is the patient
euthyroid, hyperthyroid or hypothyroid?
A synthesis of these two observations gives a simple
clinical classification of the vast majority of thyroid
swellings, as follows.
• Smooth, euthyroid enlargement of the thyroid
gland: this is the ‘physiological’ goitre, which
tends to occur at puberty and pregnancy.
Nodular, euthyroid gland: this is the common nod-
•
ular goitre, there being either a solitary nodule or
multiple nodules.
•
Smooth, hyperthyroid goitre: primary hyperthy-
roidism (Graves’ disease).
Nodular hyperthyroid goitre: toxic nodular goitre.
•
The less common findings are as follows.
• Smooth, firm enlargement with myxoedema:
Hashimoto’s disease. Usually in a middlewoman, and the gland is sometimes asymmetrical
and irregular.
Invasive enlargement, hard: carcinoma.
•
Riedel’s thyroiditis and acute thyroiditis are
uncommon.
aged
Outline oftreatment
ofgoitre
Euthyroid nodular enlargement
T4 replacement (levothyroxine) may be effective by
reducing TSH secretion, and so suppressing further
enlargement. It is best given following thyroidectomy
to suppress enlargement of the remaining gland
tissue.
Single euthyroid nodule
In the patient with a single nodule in the thyroid, this
may be a solitary benign adenoma, a malignant
tumour or, most likely of all, a cyst or nodule in a thyroid showing the histological changes of a nodular
goitre. Half of all solitary nodules are in fact prominent areas of multinodular goitres.
Historically all solitary nodules were excised to
make a diagnosis. Nowadays, ultrasound combined
with fineferentiate nodules that should be excised from benign
lesions. Cysts are aspirated and checked at an interval
to ensure that they do not redistinguish benign follicular adenomas from follicular carcinomas, so these are often excised to provide
definitive histology.
needle aspiration cytology can usually dif-
collect. Cytology cannot
Hyperthyroidism
The available therapy comprises:
• Antithyroid drugs, of which carbimazole is the
drug of choice.
•
β- adrenergic blocking drugs.
• Antithyroid drugs combined with subsequent
thyroidectomy.
• Radioactive iodine- 131.
Multinodular goitre
Thyroidectomy is advised in patients with an
enlarged, euthyroid, nodular goitre when there are
symptoms of tracheal compression and dyspnoea.
In addition, in younger patients, it is reasonable to
advise surgery because of the danger of haemorrhage
into a thyroid cyst with the risks of acute tracheal
compression. If there is retrosternal extension in a
younger patient, then surgery should be advised as
delay will only make surgery more challenging. The
patient may also be concerned with the cosmetic
appearance of the swollen neck.
In elderly patients with a long- standing goitre
that is symptomless, it is good practice to pursue a
non- operative approach.
Antithyroid drugs
Carbimazole and propylthiouracil are the most commonly used antithyroid drugs in the UK. Carbimazole
is used as the first- line treatment with propylthiouracil being used in pregnancy or in patients intolerant to
carbimazole. There is rapid regression of symptoms,
the patient beginning to feel better and to gain weight
with reduction of tachycardia within 1–2 weeks.
Treatment is continued for 12 months and may be
combined with levothyroxine (so- called ‘block and
replace therapy’). If symptoms recur, a further
6 months’ treatment is given, after which surgery is
advised. Unfortunately, a high relapse rate (up to
60%) occurs after terminating the treatment, even if
The thyroid 401
https://t.me/medicina_free
this is prolonged for 2 or more years. Medical treatment alone is, therefore, usually confined to the treatment of primary hyperthyroidism in children and
adolescents.
The toxic effects of carbimazole include a rash,
fever, arthropathy, lymphadenopathy and agranulocytosis; the last is a dangerous and potentially lethal
complication but occurs in well under 1% of patients.
The first symptom is a sore throat and patients on
carbimazole must be warned to discontinue treatment immediately if this occurs and to report to hospital. Granulocyte colonyrequired.
stimulating factor may be
β- Adrenergic blocking drugs
In patients with severe hyperthyroidism, propranolol
induces rapid symptomatic improvement of the cardiovascular features by blocking sympathetic overactivity, while the hyperthyroidism comes under control
with specific antithyroid therapy.
Drugs andsurgery combined
The majority of adult patients in the UK are
treated with preliminary carbimazole until euthyroid; relapse after medical therapy is an indication for radioactive iodine or thyroidectomy. Most
patients will be euthyroid following a course of
drug therapy although 50% will relapse and
require further drug treatment at a later stage.
Radioiodine is associated with a higher relapse
rate than surgery, and a high incidence of lateonset hypothyroidism, but may be more suitable
for treating older patients. It is not associated
with increased malignancy.
The surgical management of primary hyperthyroidism (Graves’ disease) is now usually limited to
younger patients in their late teens or early twenties
who have relapsed following their second course of
drug treatment and who are looking for a longcure for their disease. The historical operation for primary hyperthyroidism had been subtotal thyroidectomy in an attempt to render the patient euthyroid
with no need for exogenous thyroxine. Unfortunately,
most patients will require thyroxine replacement in
time, and, by leaving too much thyroid tissue in situ,
there is a risk of recurrence. As a result, total thyroidectomy has become the operation of choice for these
patients in the same way as for patients with multinodular goitre.
term
Radioactive iodine
From the patient’s point of view, this is the most
pleasant treatment, as all the patient has to do is
swallow a glass of water containing the radioiodine.
There is no need for prolonged treatment with drugs
or the risk of operation; it is particularly useful in
recurrence of hyperthyroidism after thyroidectomy. It
usually takes 2–3 months before the patient is rendered euthyroid. Antithyroid drugs, with or without a
β-
blocker, may be used to control symptoms during
this time.
There is a theoretical risk of malignant change in
the irradiated gland, although it is very uncommon.
There is no convincing evidence of an increased risk
of developing an unrelated cancer in the long term
with the dose of radioactive iodine administered.
Nevertheless, it is current practice not to use radioiodine in young women who may become pregnant
during treatment, as there is a very real danger of
affecting the infant’s thyroid. It is also not used when
there is thyroid eye disease or there are concerns
about tracheal compression. Another disadvantage
of this treatment is the high incidence of late hypothyroidism, which requires replacement therapy
with T4.
Complications
ofthyroidectomy
In addition to the hazards of any surgical operation,
there are special complications to consider following
thyroidectomy. These can be divided into hormonal
disturbances (the thyroid itself and the adjacent
parathyroid glands) and injury to closely related anatomical structures.
Hormonal:
1
a
Paraesthesiae, owing to coincidental parathy-
roid removal or bruising.
b Tetany (parathyroid removal or bruising).
c Thyroid crisis.
d Hypothyroidism, owing to extensive removal of
thyroid tissue.
e Late recurrence of hyperthyroidism owing to
inadequate excision of the hyperthyroid gland.
2 Damage to related anatomical structures:
a Recurrent laryngeal nerve injury.
b Injury to trachea.
c Pneumothorax.
402 The thyroid
https://t.me/medicina_free
3 The complications of any operation, especially:
Haemorrhage.
a
b
Sepsis.
c
Postoperative chest infection.
Hypertrophic scarring (keloid).
d
Some of these complications require further con-
sideration here.
Hypoparathyroidism
This may result from inadvertent removal of the parathyroids or their injury during operation. The patient
may develop paraesthesiae or tetany (see Chapter40)
a few days postoperatively with typical carpopedal
spasms, which may be induced by tourniquet around
the arm (Trousseau’s sign, see Chapter40), and a positive Chvostek’s sign (see Chapter40); this is elicited by
tapping lightly over the zygoma, when the facial muscles will be seen to contract.
Treatment
Treatment consists of giving oral calcium together
with vitamin D derivatives (ergocalciferol or alfacalcidol) or 10 mL of 10% calcium gluconate intravenously if symptoms are severe. Often, the tetany is
transient and the injured parathyroids recover; in
other cases, permanent treatment with alfacalcidol is
required. Parathormone is not used.
In addition to frank tetany, which occurs in about
1% of cases, milder degrees of hypoparathyroidism
may occur and may present with mental changes
(depression or anxiety neurosis), skin rashes and
bilateral cataracts. Low postoperative calcium is
treated by the administration of oral calcium and/or
vitamin D daily by mouth.
Thyroid crisis
An acute exacerbation of hyperthyroidism seen immediately postoperatively is now extremely rare because of
the careful preoperative preparation of these patients. It
is a frightening phenomenon, with mania, hyperpyrexia and marked tachycardia, which may lead to death
from heart failure. The cause is not fully understood,
but it may be due to a massive release of thyroxine from
the hyperactive gland during the operation.
Treatment
Treatment comprises heavy sedation, propranolol,
antithyroid medication, iodine and cooling by means
of ice packs.
Recurrent laryngeal nerve injury
The recurrent laryngeal nerve lies in the groove
between the oesophagus and trachea in close relationship to the inferior thyroid artery (Figure 39.2).
Here it is at risk of division, injury from stretching or
compression by oedema or blood clot.
If one nerve alone is damaged, the patient may
have little in the way of symptoms apart from slight
hoarseness because the opposite vocal cord compensates by passing across the midline during phonation.
(a) (b) (c)
Figure39.2 The relationship of the recurrent laryngeal nerve to the thyroid gland and the inferior thyroid artery.
However, if both recurrent nerves are damaged there
https://t.me/medicina_free
is almost complete loss of voice and serious narrowing
of the airway; a temporary tracheostomy may be
required, although an incomplete injury may recover
in time. It is estimated that the nerve is injured in
about 2–3% of thyroidectomies.
Vocal cord assessment by flexible nasendoscopy
should be performed prior to thyroid surgery, and is
essential for patients with known malignancy, previous neck surgery and for patients with hoarseness or
stridor.
It is also possible to injure the external branch of
the superior laryngeal nerve resulting in a lower, less
powerful voice.
Haemorrhage
If this occurs shortly after thyroidectomy, it can be
life- threatening, as bleeding into the thyroid bed and
haematoma formation cause respiratory distress by
causing venous congestion and laryngopharyngeal
oedema. Symptoms and signs include dysphagia,
odynophagia, respiratory distress, neck swelling, oozing from the wound and pain.
Treatment
This may be an extreme emergency and must be dealt
with at once by decompressing the neck in the ward.
The skin and the subcutaneous sutures are removed,
the wound is opened and the blood clot expressed.
The patient can then be transferred to theatre, anaesthetized, bleeding points secured and the wound
resutured.
Thyroid tumours
Classication
Benign
• Follicular adenoma.
The thyroid 403
d
Medullary carcinoma.
e
Lymphoma (rare).
Secondary:
2
a
Direct invasion from adjacent structures, for
example, oesophagus.
Rare site for blood- borne deposits e.g. from
b
renal carcinoma.
Benign adenoma
Although benign encapsulated nodules in the thyroid
gland are common, the majority are part of a nodular
colloid goitre. A small percentage represent true
benign adenomas, of which 10% are ‘hot nodules’, that
is, they produce excess thyroxine. Thyroid adenomas
are four times more common in women.
Thyroid carcinoma
Thyroid carcinoma affects women three times as
often as men and the incidence is rising. Risk factors include endemic goitre, radiation exposure in
childhood, familial, Hashimoto’s thyroiditis (lymphoma), familial adenomatous polyposis and
Cowden syndrome
6 per 100000 and long- term survival rates following treatment are excellent. Ten- year survival rates
for papillary and follicular cancer are over 90% and
80%, respectively. Papillary and follicular cancer,
together referred to as ‘differentiated thyroid cancer’, account for approximately 90% of all thyroid
cancers.
Differentiated thyroid cancer is usually curable
when detected at an early stage. The high cure rate
can be attributed to a multidisciplinary approach,
including specialist surgery, radioiodine ablation,
TSH suppression and, finally, the use of thyroglobulin
as a thyroid- specific tumour marker (see later in this
chapter). Despite this management strategy, a small
number of patients will develop recurrence. Half of all
thyroid cancer deaths are due to respiratory failure
secondary to either pulmonary metastasis or airway
obstruction.
9
. It has an incidence of around
Malignant
1 Primary (five main types):
a Papillary adenocarcinoma.
b Follicular adenocarcinoma.
c Anaplastic.
9
Cowden syndrome: Autosomal dominant condition caused
by mutation in PTEN tumour suppressor gene characterised
by the development of multiple hamartomas in skin and
mucous membranes, but also cancers of the thyroid, breast
and uterus, among others. Named after the Cowden family
in whom it was rst described.
404 The thyroid
https://t.me/medicina_free
Pathology
Papillary carcinoma
This is the most common type of thyroid cancer, constituting 80% of thyroid cancers. It occurs in young
adults, adolescents or even children. It is a slowgrowing tumour and lymphatic spread occurs late.
Deposits in the regional lymph nodes may be solitary
and in the past have been mistakenly regarded as lateral aberrant thyroid tissue. However, a careful search
of the thyroid gland will reveal a welltumour in the ipsilateral lobe.
differentiated
Follicular carcinoma
This occurs in young and middle- aged adults, the
incidence peaking in the fifth decade, and accounts
for 10% of thyroid cancers. It is more common in
areas where endemic goitres are common. It has a
tendency to spread via the bloodstream particularly
to bones and lungs; lymph node spread is
uncommon.
Medullary carcinoma
This arises from the parafollicular C cells and secrete
calcitonin.
other thyroid tumours, has a roughly equal sex distribution; it accounts for 5% of thyroid cancers. It
may be familial (in 25% of cases) and may be associated with other cancers in the multiple endocrine
neoplasia syndrome (type II, associated with phaeochromocytoma and either parathyroid tumours or
neurofibromas; see Chapter40). The characteristic
finding is deposits of amyloid between the nests of
tumour cells.
The disease is usually multicentric and bilateral
in all familial forms, and is associated with C cell
hyperplasia. In contrast, the sporadic form is usually unifocal with no associated hyperplasia. The
tumour cells produce calcitonin, which acts as a
tumour marker and can be used as a screening test
in syndromic families or to detect recurrence in followtion cytology of medullary thyroid carcinoma may
be diagnostic.
10
Calcitonin acts to lower serum calcium, stimulating
osteoblast and inhibiting osteoclastic activity in bones,
among other actions.
10
It may occur at any age and, unlike
up of patients after surgery. Fine- needle aspira-
Anaplastic carcinoma
This occurs in the elderly, thus reversing the usual
state of affairs, in that the more malignant tumours of
the thyroid occur in the older age group. Rapid local
spread takes place with compression and invasion of
the trachea. There is early dissemination to the
regional lymphatics and bloodstream spread to the
lungs, bone and brain. It accounts for around 2% of
thyroid cancers.
Lymphoma
Rarely a thyroid tumour may be a non- Hodgkin’s
lymphoma.
Clinical features
Tumours may present like other goitres as a lump in
the neck, often more rapidly growing. Dysphagia is
uncommon, and suggestive of an anaplastic tumour;
more common is the complaint that swallowing is
uncomfortable. Pain may occur with local infiltration,
and hoarseness is suggestive of infiltration of the
recurrent laryngeal nerve. Lateral cervical lymph
nodes may be palpably enlarged. The patients are
usually euthyroid. Ultrasound- guided core needle
biopsy or fine- needle aspiration cytology is used to
confirm the diagnosis.
Treatment ofdifferentiated
thyroidcancer
Surgery
The management of a patient with thyroid cancer
should be the responsibility of a multidisciplinary
team. Wella combination of surgery, thyroid suppression by
levothyroxine and radioiodine.
Total thyroidectomy is recommended for patients
with tumours greater than 4cm in diameter (pT3),
or tumours of any size in association with any of
the following characteristics: multifocal disease,
bilateral disease, extra- thyroidal spread (pT4a),
familial disease, and those with clinically or radiologically involved nodes and/or distant metastases.
Furthermore, radioiodine ablation is facilitated by
total thyroidectomy.
Thyroid lobectomy is, therefore, appropriate surgery for unifocal, papillary tumours less than 4cm in
differentiated tumours can be treated by
Соседние файлы в папке Библиотека им академика М.И. Перельмана