GOITRE, simple solitary nodule and toxic solitary nodule

The term goitre is derived from latin word  gutter- that means throat and describes generalised enlargement of thyroid gland.

I. Simple Goitre

–  Diffuse Hyperplastic (Physiological)

Pubertal

Pregnancy

- Simple Solitary nodule (Adenoma)

- Simple Multinodular Goitre

II. Toxic Goitre

•      Diffuse Toxic Goitre (Graves’ disease)

•      Multinodular with secondary toxicity

•      Toxic adenoma

III. Neoplastic

•      Benign

•      Malignant

IV. Inflammatory

•      Autoimmune – Hashimoto’s thyroiditis

•      Granulomatous – de Quervein’s thyroiditis

•      Fibrosing – Reidel’s thyroiditis

•      Infective – Acute    (bacterial, viral, subacute thyroiditis)

- Chronic  (tuberculous, syphilitic)

V. Others     –  Amyloid goitre

SOLITARY NODULE

Any single focal lesion in the thyroid gland

DD for solitary nodule

1. Follicular adenoma (Simple adenoma thyroid)

2. Carcinoma (Papillary Ca, Follicular Ca)

3. Colloid goiter

4 Toxic nodule

5. Thyroiditis – Hashimoto’s thyroiditis

Reidel’s thyroiditis

6 Any solitary Cyst

Incidnce

3 – 4% of population

Clinical features

Swelling in thyroid region

Symptoms of hyperthyroidism may or may not be present

Non toxic or simple solitary nodule   (Adenoma of thyroid)

Thyroid adenomas  are common, solitary nodules in the thyroid.

They can occur at any age, but usually young individuals.

Females out number males by a ratio of 3 or 4 : 1.

Simple adenomas (Non toxic) appear as Solitary nodules

Grossly, the tumor may be 1 to 10 centimeters in size.

It is soft and fleshy and may have cystic areas.

It is almost always encapsulated and solitary.

The majority of benign tumours of the thyroid gland arise from the follicular epithelium and so, are follicular adenomas.

Clinically, adenomas may:

•      cause pressure symptoms in the neck

•      suddenly enlarge and become painful due to intralesional haemorrhages

•      cause hyperthyroidism – but unassociated with the ophthalmopathy seen in Grave’s disease, take up radioactive iodine – appear as “hot” nodules, and named as toxic solitary nodule.

Pathogenesis

Stimulation of thyroid gland

  • TSH is not the only factor which stimulates thyroid follicular cell proliferation.
  • There are other growth factors, including immunoglobulins exert an influence over the thyroid.
  • The heterogenous structural and functional response in the thyroid resulting in characteristic nodularity may be due to the presence of clone of cells particularly sensitive to growth stimulation.

Predisposing factors of goitre

Iodine deficiency

Daily requirement is 0.1 to 0.15 mg. Deficient in mountain areas like Himalayan belt

Calcium is also goitrogenic

Dyshormonogenesis

Often there is a family history suggesting genetic defect

Goitrogenic vegitables

Cabbage,kale and rape which contain thiocyanate

Certain drugs

Para amino salicylic acid and antithyroid drugs

Natural history of goitre :

•         Persistant growth stimulation leads to diffuse hyperplasia, wherein all lobules are composed of active follicles and Iodine uptake is uniform.

•         This is a diffuse hyperplastic goitre which may persist for a long time, but is reversible if simulation stops.

•         Later as a result of fluctuating stimulation, a mixed pattern develops with areas of active lobules and areas of inactive lobules.

•         Active lobules become more vascular and hyperlastic until haemorrhage occurs causing central necrosis and leaving only a surrounding rind of active follicles.

•         Necrotic lobules coalesce to form nodules filled either with Iodine free colloid or a mass of new inactive follicles.

•         Continual  repetition of this process results in nodular goitre.

The nodules are inactive in the multinodular goiter, but the internodular tissue is active.

The adenoma represents a initial response to TSH but often either become or are to begin with autonomous.

Initially, the amount of thyroid hormone secreted by the adenoma may be insufficient to cause metabolic disturbance.
However, as the adenoma grows larger and if it remains functional, the patient may exhibit signs of hyperthyroidism.
In such cases, do to feedback inhibition of TSH synthesis, the remainder of the thyroid may become atrophic.,

Clinical features of Solitary nodule

Age – In younger individuals – Nodule is more likely to  become malignant

•      Sex – Less frequent in males

But if occurs – is more likely to be malignant

•      Duration of nodule-

Present for long time – may be a benign condition..

Note  progress of nodule, pain, obstructive symptoms

Sudden appearance – Carcinoma

Rapid enlargement        – Haemorrhage into nodule  -Carcinoma

Painful                             – Haemorrhage into nodule  Carcinoma

- Hashimoto’s thyroiditis

Rule out toxic features         –   Chest pain

-    Palpitation

-   Tremors

Local Examination

•      Solitary swelling in thyroid

•      Moves up with deglutition

•      Margins well defined

•      Consistency – usually firm

•      Transverse Mobility restricted

•      Enlarged lymph nodes may be present

Hard in consistency, enlarged lymph nodes, fixity  –Carcinoma

Toxic solitary nodule

May be a part of generalized nodularity or true toxic adenoma.  It is Autonomous.

Autonomous Toxic nodule: ↑ T3 &  ↑T4

↓ TSH

Surrounding normal thyroid tissue suppressed and inactive and become atrophied.

Investigations:

1. FNAC “ Investigation of choice”

By F.N.A.C. we can differentiate

Colloid goitre

Thyroiditis

Malignant / Benign cystic lesions

Malignant lesions

Differentiation between follicular adenoma and  follicular carcinoma is not possible in FNAC

2. X’ray neck To rule out tracheal deviation and calcification

3. Xray chest To rule out retrostrenal involvement and lung secondaries in case of carcinoma

4. ULTRASONOGRAM:   Solid or cystic swelling

5. THYROID Profile:    Serum T3, T4, TSH

6. AUTOANTIBODY TITRE:  If  ↑ – it indicates autoimmune thyroiditis.

TREATMENT OF SOLITARY NODULE

Follicular adenoma             Hemithyroidectomy

•      Carcinoma                           Near total Thyroidectomy

•      Toxic nodule                       Hemithyroidectomy / Radioactive iodine

•      Hashimoto’s thyroiditis               Thyroxine, Steroid therapy, Surgery

•      Reidel’s thyroiditis                       Thyroxine, Isthmusectomy

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