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Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1060_Библиотеки_им_академика_М_И_Перельмана

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Examination of Thyroid
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U/S neck for thyroid and neck nodes. X-ray neck to see calcifications (speckled fine calcification in papillary carcinoma of thyroid; coarse, ring-like calcification in MNG) and tracheal deviation.
FNAC thyroid and lymph node. CT neck in malignancies or large goitre. Trucut biopsy if two trials of FNAC are inconclu-
sive. It can injure deeper structures like recurrent laryngeal nerve and also can cause hemorrhage.
Frozen section biopsy on table and proceed may be needed to rule out malignancies.
Special blood analysis: Serum calcitonin, serum thyroglobulin estimation in neoplasms of thyroid.
Role of ultrasound (U/S) in thyroid diseases
To detect number, size, nature of the nodules (cystic/ solid/complex) (complex means cystic and solid together— more suspicious of carcinoma). Size up to 2 mm can be detected. U/S guided FNAC is very useful. U/S at regular intervals is advisable to observe a small nodule in thyroid. To detect recurrent nodule. To find out the invasion/spread/vascularity/status of carotid artery and internal jugular vein. To find out enlarged lymph nodes in neck.
Role of FNAC in thyroid swelling
Highly sensitive in papillary carcinoma of thyroid and also its nodal spread. Useful to differentiate between benign and malignancy (Fig. 14.39). Useful in lymphoma/anaplastic carcinoma/medullary carcinoma thyroid/Hashimotos thyroiditis. It is not very useful in follicular carcinoma as it is difficult to differentiate it from follicular adenoma as capsular invasion/vascular invasion is main feature in follicular carcinoma.
Note: On table frozen section biopsy is useful in negative
FNAC but doubtful cases. Definitive procedure is undertaken once frozen section report comes on table. But in frozen section biopsy itself, 15% of follicular carcinoma report may be inconclusive or negative which causes difficulty in taking decision. In such occasion hemithyroidectomy is done and once histo­logy report of follicular carcinoma is obtained comple­tion thyroidectomy is done usually immediately within a week. If biopsy report is delayed then completion thyroidectomy is done after 6 weeks.
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Fig. 14.39: FNAC thyroid is an important
investigation in thyroid diseases.
Trucut biopsy gives tissue diagnosis but danger
of haemorrhage and injury to vital structures like trachea, recurrent laryngeal nerve, vessels are likely.
Solitary Thyroid Nodule
It is a single palpable nodule in thyroid on clinical examination, in an otherwise normal gland. Causes:
(1) Thyroid adenomas—Follicular—common (40% of actual single nodule excluding solitary nodule of MNG); Hurthle cell. (2) Papillary carcinoma of thyroid—15%. (3) Only one nodule palpable in an underlying multinodular goiter – commonest cause
only clinically—50%. (4) Thyroid cyst. Types:
Based on function: (1) T oxic solitary nodule. (2) Non­toxic solitary nodule.
Based on radioisotope study: (1) Hot—Means auto- nomous toxic nodule. (2) Warm—Normally function- ing nodule. (3) Cold—Non-functioning nodule; may be malignant-20% (need not be always). Cold nodule may be due to malignancy, thyroiditis, thyroid cyst or haemorrhage. (4) Hot or warm in
but cold in I
123
scan—commonly they are malignant.
Note: Thyroid nodule in children and elderly can be
malignant. Rapid enlargement of thyroid nodule can be malignant. 30% of solitary nodules are cystic.
Features: Single nodule palpable in one or other lobes of the thyroid which is usually smooth, globular, firm
99m
T echnetium scan
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SRB’s Clinical Surgery
with well-defined margin. Overlying skin is normal. Lahey’s test does not show any other nodules in posterior part of the gland. Tracheal deviation towards opposite side is common-confirmed by trail sign, three finger test and auscultation. U/S neck is very useful. FNAC is essential. When FNAC is inconclusive T rucut needle biopsy may be done but it can cause pain/ bleeding/recurrent laryngeal nerve injury . T3, T4, TSH are done to find out the function. Radioisotope study
123/I131/ 99m
(I
Tc) may be often needed. CT scan or MRI neck is done only in selected cases but not routinely (large swelling/to see vascularity/retrosternal extension are the indications) (Figs 14.40A to 14.42).
Indications for surgery in solitary nodule thyroid
Malignant nodule Follicular neoplasm Toxic nodule in young Nodules with obstruction Recurrent cystic nodule Complex cyst (both solid and cystic component) Cosmetics.
Possible features of suspected malignancy in solitary nodule thyroid
Any nodule can be malignant whether nodule is hard/ firm/cystic/small/large/asymptomatic Rapid onset/rapid recent increase in size Hoarseness of voice/dysphagia/stridor/dysphagia Fixity of the nodule Palpable significant neck nodes.
A
Diffuse Hyperplastic Goitre
Initial persistent increase in TSH level causes diffuse active lobules. In late stages of diffuse hyperplasia, TSH stimulation decreases and many follicles become inactive and gets filled with colloid , called as colloid
goitre. As diffuse hyperplastic goitre is a reversible stage, l- thyroxine is beneficial.
Nodular Goitre
Pathogenesis
Persistent TSH stimulation → Diffuse hyperplasia of gland (all active lobules) Later with fluctuation of TSH level Mixed areas of active and inactive lobules develop Active lobules become more vascular and hyperplastic Haemorrhages occur with necrosis in the centre Nodule formation Centre of nodule is inactive and only margin is active, i.e.
B
Figs 14.40A and B: Solitary nodule involving isthmus.
internodular tissue is active Formation of many nodules Multi-Nodular Goitre (MNG). Other factors involved are growth stimulating immunoglobulins and growth prone cell clones.
Features
It is a slowly progressive disease with many years of history; multiple nodules of different sizes are formed in both lobes, also in isthmus, which is firm,
Examination of Thyroid
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A
B
Figs 14.41A and B: Solitary nodule right
lateral lobe. It is a clinical entity.
nodular, nontender, moves with deglutition; recent increase in size signifies malignant transformation or haemorrhage (Figs 14.43 and 14.44). Investigations are T3, T4, TSH, U/S neck, FNAC, X-ray neck shows ring or rim calcification.
Complications of MNG
Secondary thyrotoxicosis (30%); follicular carcinoma of thyroid (10%); haemorrhage in a nodule; tracheal obstruction; calcification.
Fig. 14.42: Solitary nodule thyroid causes deviation of
trachea to opposite side.
Fig. 14.43: Diagrammatic representation of
multinodular goitre.
Thyroid cyst
It is thyroid swelling which is cystic in nature eliciting positive fluctuation. Common cause is colloid degeneration. 30% of solitary nodules are cystic. 15% cystic swellings in thyroid are malignant. A cyst if contains both solid and cystic areas is called as complex cyst which is more likely to be malignant. FNAC may cause regression in simple cyst. Surgery is needed if recurrence occurs after three repeated aspirations. Surgery is indicated in complex cyst and if cyst is more than 4 cm in size.
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Fig. 14.44: Large multinodular goitre.
Thyrotoxicosis and Hyperthyroidism
SRB’s Clinical Surgery
It is complex of symptoms and signs due to raised levels of thyroid hormones.
stimulating antibodies (Ts Ab) and long acting thyroid stimulator (LATS) cause pathological changes in the thyroid. Histologically there is acinar cell hypertrophy and hyperplasia with absence of normal colloid in the tall columnar epithelium (normal is flat epithelium with colloid). As cells are empty, they look vacuolated. Tissues are highly vascular . Exophthalmos producing substance (EPS) causes Grave’ s ophthalmopathy (Fig.
14.45).
Types
(1) Diffuse toxic goitre-(Grave’s disease, Basedow’s disease, Primary thyrotoxicosis). (2) Toxic multi- nodular goitre (Secondary thyrotoxicosis; Plummer disease). (3) Toxic nodule. (4) Hyperthyroidism of
rarer causes: Thyrotoxicosis factitia- drug induced due to intake of L-thyroxine more than normal; Jod Basedow thyrotoxicosis—because of consumption of large doses of iodides given to a hyperplastic endemic goitre; Autoimmune thyroiditis or de‘ Quervain’s
thyroiditis; Occasionally carcinoma thyr oid; Neonatal thyrotoxicosis—It subsides in 3-4 weeks as T sAb titres
fall in the baby’ s serum. Note: Wolf-Chaikoff effect— iodides inhibit the further release of hormone causing hypothyroidism. It is eight times more common in females; occurs in any age group; primary type is seen commonly in younger age group; secondary is common in older age group. Grave’s disease is an autoimmune disease with increased levels of specific antibodies in the blood (TSH receptor antibodies). It is often associated with vitiligo. It is often familial. Thyroid stimulating immunoglobulins (TSI)/thyroid
Fig. 14.45: Thyrotoxicosis (primary). Note the exophthalmos
and also toxic thyroid enlargement.
Symptoms of Hyperthyroidism
Gastrointestinal system: Weight loss in spite of increased appetite; diarrhoea (due to increased activity at ganglionic level).
Cardiovascular system: Palpitations, chest pain; shortness of breath at rest or on minimal exertion; angina; irregularity in heart rate; cardiac failure.
Neuromuscular system: Undue fatigue and muscle weakness, exaggerated tendon reflexes, myasthenia like syndrome; tremor, hyperkinesias, increased sweating.
Skeletal system: Increase in linear growth in children. Genitourinary system: Oligo- or amenorrhoea;
occasional urinary frequency. Integument: Hair loss; pruritus; palmar erythema.
Examination of Thyroid
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Wayne’s Diagnostic Indices (Clinical)
Symptoms Present Absent
1 Dyspnoea on effort +1 2 Palpitation +2 3 Tiredness +2 4 Preference for heat –5 5 Preference for cold (Heat intolerance) +5 6 Excessive sweating +3 7 Nervousness +2 8 Appetite increased +3 9 Weight decreased +3
Signs Present Absent
1 Bruit over thyroid +2 2 Exophthalmos +2 3 Lid retraction +2 4 Lid lag +1 5 Hyperkinetic movements +4 –2 6 Fine finger tremors +1 7 Hands Hot +2 –2
Moist +1 –1 8 Atrial fibrillation +4 9 Pulse rate 80/minute. –3
80-90/minute 0 More than 90/minute +3
10 Palpable thyroid
+3
< 11 points –non toxic 11-19 –equivocal > 19 points –toxic goitre
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Psychiatry: Irritability; nervousness; insomnia.
Sympathetic overactivity causes dyspnoea, palpitation, tiredness, heat intolerance, sweating, nervousness, increased appetite and decrease in weight. Because of the increased catabolism they have increased appetite, decreased weight and so also increased creatinine level which signifies myopathy (due to more muscle catabolism). Fine tremor is due to diffuse irritability of grey matter. Thrill is felt in the upper pole of the thyroid and also bruit is heard on auscultation. It is because superior thyroid artery enters the gland superficially in upper pole, and so thrill and bruit can easily be assessed. Inferior thyroid artery enters the gland in lower pole at deeper plane and so thrill cannot be felt (Fig. 14.46).
Signs of Hyperthyroidism
(1) Eye signs in toxic goitre (Refer above). (2) Cardiac manifestations: Tachycardia is common. Sleeping
pulse rate is usually checked for three consecutive
Fig. 14.46: Diffuse toxic goitre. Note the involvement
of both lobes bilaterally.
nights and average is taken as the value; ectopic; pulsus paradoxus; wide pulse pressure; multiple extrasystoles; paroxysmal atrial tachycardia; paroxysmal atrial fibrillation; persistent atrial fibrillation (not responsive to digoxin). (3) Myopathy: Weakness of proximal muscles occurs, i.e. the front thigh muscles, or arm muscles; weakness is more when
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muscle contracts isometrically, i.e. either while climbing down steps, or lifting a full bucket etc. often when it is severe it resembles myasthenia gravis. Once hyperthyroidism is controlled recovery occurs. (4) Pretibial myxoedema is often a feature of primary thyrotoxicosis (It is a misnomer)—It is usually symmetrical, shiny, red thickened skin, with coarse hair; in severe cases skin of whole leg below the knee with foot and ankle is involved: it is due to deposition of myxomatous tissues (mucin like deposits) in skin and subcutaneous plane; it might or might not regress completely after treatment for toxicity; it is associated with exophthalmos with high levels of thyroid stimulating antibodies. (5) Thyroid Acropachy is clubbing of fingers and toes in primary thyrotoxicosis; hypertrophic pulmonary osteoarthropathy also may develop.
Cardinal signs of toxic thyroid
• Palpable thyroid often with thrill and bruit
• Tremor of hands and tongue
• Tachycardia
• Exophthalmos
SRB’s Clinical Surgery
Thyrocardiac: Severe cardiac damage resulting from hyperthyroidism usually secondary type requires proper opinion from cardiologists and treatment with propranolol.
thyrotoxicosis should be suspected if the clinical
T
3
picture is suggestive of toxicosis, but routine tests for thyroid function are within normal range.
Investigations
(1) Serum T3 and T4 levels are very high. TSH is very low or undetectable. Sometimes, only T3 level is increased and is called as T3 toxicosis. In T3 toxicosis, free T3 estimation is important. Radioisotope study
131
by I
will show more uptake, i.e. hot nodules or hot areas. This is very useful to detect autonomous solitary toxic nodule. (2) TRH estimation. (3) ECG—T o look for cardiac involvement and if required opinion from cardiologists’ is taken and cardiac problems are managed accordingly . (4) Total count and neutrophil count are very essential base line investigations before starting antithyroid drugs (as it may cause agranulo­cytosis).
T oxic nodule: It is a solitary overactive nodule. There is an autonomous hypertrophy and hyperplasia of the part of the gland where there is a nodule. [It is not due to Thyroid stimulating antibody (Ts Ab)]. Here high levels of circulating thyroid hormones suppress TSH secretion and so normal thyroid tissue
Differential Diagnosis of Thyrotoxicosis
Anxiety neurosis—hands are cold and moist, sleeping pulse rate is normal, thyroid enlargement is not present; phaeochromocytoma; malabsorption syndrome; dia­betes mellitus.
surrounding the nodule is been suppressed and inactive.
Toxic thyroid in pregnancy and children: Radio­iodine therapy is absolutely contraindicated in
pregnancy (High risk to foetus) and children (high risk of developing thyroid carcinoma).
Differentiating Points Between Primary and Secondary Hyperthyroidism
Primary thyrotoxicosis Secondary thyrotoxicosis
1. Symptoms appear first, then swelling. 1. Swelling appears first
2. Goitre is diffuse, smooth, firm or soft, 2. Swelling is large nodular, obvious both lobes are involved 3. Symptoms appear after long time, which is less
3. There is thrill and bruit severe and slowly progressive compared to
4. Features are much more severe compared primary toxicosis. to that of secondary toxicosis. 4. Cardiac features are more common.
5. Eye signs and exophthalmos are common. 5. Eye signs are not common.
6. As it is an autoimmune disease, there may be hepatosplenomegaly.
Histologically, there is hyperplasia of acini, lined by columnar epithelium, often containing vacuolated colloid.
Thyroid Neoplasms
Classification of Thyroid Neoplasm
Benign: Follicular adenoma; Hurthle cell adenoma; colloid adenoma—commonest; papillary adenoma— its existence is doubtful. It is invariably low grade
Examination of Thyroid
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papillary carcinoma.
Malignant (Dunhill classification): (a) Differentia- ted—Papillary carcinoma 60%); Follicular carcinoma
(7%); papillofollicular carcinoma behaves like papillary carcinoma of thyroid; Hurthle cell carcinoma behaves like follicular carcinoma. (b) Undifferentiated. Anaplastic carcinoma (13%). (c) Medullary carcinoma (6%). (d) Malignant lymphoma (4%). (e) Secondaries in thyroid (rare)—from colon, kidney , melanoma (Fig.
14.47). Aetiology of thyroid malignancy: (1) Radiation either
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Fig. 14.47: Carcinoma thyroid. Note the superficial
tissue infiltration. Dilated veins are also seen.
external or radioiodine can cause papillary carcinoma thyroid. There was increased incidence of thyroid carcinoma among children following exposure to ionizing radiation after the Chernobyl nuclear disaster in Ukraine in 1986. Irradiation to head and neck region used to be the therapy for benign conditions like ade­noids, acne vulgaris, thymus enlargement, haeman­giomas which predisposed papillary carcinoma of thyroid. Radiotherapy for Hodgkin’s lymphoma in younger age group may later cause papillary carcinoma of thyroid. (2) Pre-existing multinodular goitre. It turns into follicular carcinoma of thyroid. (3) Medullary carcinoma of thyroid commonly and 6% of papillary carcinoma of thyroid can be familial. (4) Hashimoto’s thyroiditis may predispose to papillary carcinoma of
Fig. 14.48: Carcinoma thyroid in a male patient
showing vascularity.
thyroid and also NHL (Fig. 14.48).
Papillary Carcinoma
It is 60% common; common in females (3: 1) and young age group. TSH levels in the blood of these patients are high and so it is called as hormone dependent tumour. It is a slowly progressive and less aggressive tumour. It is commonly multicentric. It spreads within the gland through intrathyroidal lymphatics to other lobe, comes out of the capsule and spreads to lymph nodes. Usually there is no blood spread.
Types: Occult (< 1.5 cm); Intrathyroidal; Extrathyroi­dal; Micropapillary carcinoma is less than 1 cm in size or clinically not detectable.
Gross: It can be soft, firm, hard, and cystic. It can be solitary or multinodular. It contains brownish black fluid.
Microscopy: It shows cystic spaces, papillary projections with psammoma bodies, malignant cells with ‘Orphan Annie eye’ nuclei (intranuclear cytoplasmic inclusions, nuclear grooving).
Clinical features: (1) Soft or hard or firm, solid or cystic, solitary or multinodular thyroid swelling. (2) Compression features are uncommon in papillary carcinoma thyroid. (3) Often discrete lymph nodes in the neck are palpable.
Diagnosis: FNAC of thyroid nodule and lymph node,
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Fig. 14.49: Papillary carcinoma of thyroid with lymph
nodal spread.
SRB’s Clinical Surgery
to see psammoma bodies, nuclear changes; Radio­isotope scan shows cold nodule; TSH level in the blood is higher (Fig. 14.49).
AMES scoring
A: Age less than 40 years has got better prognosis. M: Distant metastasis. E: Extent of the primary tumour. S: Size of the tumour. Size less than 4 cm has got
better prognosis.
AGES scoring
A: Age less than 40 years has got better prognosis. G: Pathologic grade of the tumour. E: Extent of the primary tumour. S: Size of the primary tumour. Size less than 4 cm
has got better prognosis.
Psammoma bodies are seen in
Papillary carcinoma thyroid Meningioma Serous cystadenoma of ovary
Berry’s in thyroid
Berry ligament Berry sign Berry picking
Lateral aberrant thyroid is a misnomer . It is actually secondaries in neck lymph nodes which are palpable from an occult primary from papillary carcinoma of thyroid (which is clinically not palpable).
Thyroid Paradox
Cellular tumours are soft, and cystic tumours are firm or hard (tensely cystic). It is observed in papillary carcinoma of thyroid.
Features of thyroid carcinoma
Any thyroid of any size, any texture—solid/cystic, with nodules of any number—single/multiple, in any age group can be malignant
Features of infiltration
Infiltration of strap muscles often with sternomastoid muscle Infiltration of laryngotracheal complex causing stridor and often haemoptysis Infiltration of recurrent laryngeal nerve causes hoarseness of voice Infiltration of oesophagus causes dysphagia/odynophagia (painful swallowing) Infiltration into carotid sheath causes absence of carotid pulsation—Berry’s sign Infiltration of cervical sympathetic chain causing Horner’s syndrome Rarely infiltration into cranial nerves or brachial plexus can occur
Features of lymph nodal spread
Discrete neck node involvement can occur commonly in papillary carcinoma of thyroid, often in medullary carci­noma and occasionally in follicular carcinoma. Lymph node is often cystic (20%) and contains brownish-black material in papillary carcinoma. Central neck (level VI) and mediastinal nodes often can get involved in thyroid malignancy. Primary nodes may be involved but clinically not palpable. Superior mediastinal nodes (level VII) can cause compression of SVC, recurrent laryngeal nerve with often dullness in the sternum. These nodes can get involved without palpable neck nodes. In the neck, palpable nodes are commonly levels—II, III and IV occasionally level V. Secondary nodes—clinically palpable. Only palpable neck node may be presentation without clinically palpable thyroid-secondary of occult primary (papillary) thyroid carcinoma. FNAC of the node concludes the diagnosis. Central node dissection is the common practice while doing total thyroidectomy in carcinoma thyroid especially in medullary carcinoma of thyroid.
Features of blood spread
Follicular carcinoma commonly spreads through blood to bone, lungs, and liver. Bone secondary is typical. It is well-localised, smooth, soft/hard, warm, nonmobile, vascular and pulsatile. It is common in the skull bone— frontal/parietal bone. It can occur in other bones also. Lung secondaries present with chest pain, dyspnoea and haemoptysis. Liver secondaries cause hepatomegaly and jaundice. Blood spread also can occur in medullary carcinoma of thyroid.
Examination of Thyroid
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Follicular Carcinoma
It is 17% common. It is common in females. It can occur either de novo or in a pre-existing multinodular goitre. It is a more aggressive tumour . It spreads mainly through blood into the lung, bones, liver. Bone secondaries are typically vascular, warm, pulsatile, localised, commonly in skull, long bones, ribs. It can also spread to lymph nodes in the neck (10%) occasionally.
Types: Non-invasive—blood spread is not common. Invasive—blood spread is common.
Typical feature: Angioinvasion and capsular inva­sion (Figs 14.50 and 14.51A to C).
Clinical features: Swelling in the neck, firm or hard and nodular; tracheal compression/infiltration and stridor; dyspnoea, haemoptysis, chest pain when there are lung secondaries; recurrent laryngeal nerve invol­vement causes hoarseness of voice, positive ‘Berry’s sign’ signifies advanced malignancy (Infiltration into the carotid and so absence of carotid pulsation); pulsatile, warm, well localised, vascular secondaries in the skull (frontal/parietal bones), long bones.
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A
Fig. 14.50: Follicular carcinoma of thyroid in a male patient.
It is involving mainly left lobe but it is extensive and spreading to adjacent soft tissues.
B
C
Figs 14.51A to C: Follicular carcinoma of thyroid causing
secondaries in skull. It is localized, vascular, smooth, pulsatile, warm secondaries (in skull). CT scan is head diagnostic.
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SRB’s Clinical Surgery
Investigations: Most often FNAC is inconclusive, because capsular and angioinvasion which is the main feature in follicular carcinoma cannot be detected by FNAC. Frozen section biopsy is very useful. But in 15% cases it shows negative results. U/S abdomen, Chest X-ray, X-ray bones are the other investigations required (Fig. 14.52).
Fig. 14.52: X-ray skull showing secondaries from
follicular carcinoma thyroid.
Hurthle cell carcinoma is a variant of follicular
carcinoma of thyroid which contains abundant oxyphill cells. It spreads more commonly to regional lymph nodes than follicular carcinoma of thyroid.
99m
Tc
sestamibi scan is very useful for Hurthle cell
carcinoma. It does not take up I
131
; has got poorer
prognosis than follicular carcinoma.
Differential diagnosis for carcinoma thyroid
Multinodular goitre Solitary nodule of other causes Riedel’s thyroiditis.
Note: Toothpaste colloid—follicular carcinoma; Chewing gum colloid—papillary carcinoma; Nuclear grooving— papillary carcinoma; Psammoma bodies— papillary carcinoma; Amyloid –medullary carcinoma; Follicular adenoma—aneuploid and in follicular carcinoma—diploid—DNA ploid study (Fig. 14.53).
Anaplastic Carcinoma
It is a very aggressive tumour of short duration, presents with a swelling in thyroid region which is rapidly progressive causing—stridor and hoarseness of voice; dysphagia; fixity to the skin; infiltration into the carotid sheath-positive Berry’s sign; swelling is
Fig. 14.53: Carcinoma thyroid with dilated
veins on the surface.
TNM staging for thyroid cancer
Tumour
Tx Primary not assessed T0 No primary T1 < 1 cm limited to thyroid T2 1-4 cm limited to thyroid T3 > 4 cm limited to thyroid T4 Any size extending beyond capsule.
Nodes
Nx Nodes cannot be assessed N0 No regional nodes N1 Regional nodes present N1a Same side neck nodes N1b Bilateral, midline, mediastinal nodes
Metastases
Mx Cannot be assessed M0 No metastases M1 Metastases present
Under the age of 45 years only Stage I —[any T/N and M0] and II [any T/N and M1]. After the age 45 years, Stage I, II, III and IV. Anaplastic carcinoma is always stage IV.
hard, with involvement of isthmus and bilateral lobes; FNAC is diagnostic; tracheostomy and isthmectomy has got a role to relieve respiratory obstruction temporarily . It carries poor prognosis (Figs 14.54 and
14.55).
Medullary Carcinoma of Thyroid (MCT)
It is uncommon (5%) type of thyroid malignancy. It arises from the para-follicular ‘C` cells which is