MALIGNANT THYROID

Dr. Amna AkramCMH, Multan

Thyroid cancer is a cancer originating from follicular and parafollicular cells. These cells give rise to well-differentiated and anaplastic cancers.

CLASSIFICATIONPapillary carcinoma (60%)Follicular carcinoma (20%)Anaplastic carcinoma (10%)Medullary carcinoma (5%)Malignant lymphoma (5%)Hurthle cell carcinoma is a rare type, considered a type of follicular carcinoma.

ETIOLOGYPapillary carcinoma…Radiation exposure

Follicular carcinoma…endemic goitre, a result of TSH stimulation

Medullary carcinoma…mutation in RET proto-oncogene,multiple endocrine neoplasia-type 2A and 2B

Lymphoma…autoimmune thyroiditis

RISK FACTORSHx neck irradiation in childhood

Endemic goitreHashimoto’s thyroiditisHx of thyroid adenomaFamilial thyroid CACowden’s syndromeExposure to nuclear Fallout (Chernobyl)

PRESENTATIONHistory: Thyroid carcinoma most

commonly manifests as painless, palpable, solitary thyroid nodules. These are mostly discovered on routine palpation.

Age of the patient is important at time of presentation because solitary nodules are most likely to be malignant in pt.s older than 60yrs and in younger than 30yrs.

Hoarsness suggests recurrent laryngeal nerve and vocal fold paralysis.

Dysphagia may be a sign of  impingement of the digestive tract

 Heat intolerance and palpitations suggest autonomously functioning nodules.

PHYSICAL EXAMINATIONMalignant nodules are usually hard, fixed and non-tender

Firm cervical masses are highly suggestive of regional lymph node metastases.

INVESTIGATIONSTFTsFNAC with/without USG guidanceThyroid autoantibodiesMRI/CT -if limits of goitre cannot be determined

clinically -fixed tumors -haemoptysis - DO NOT USE IODINATED CONTRAST MEDIA

STAGING Tumor: TX: cannot be assessed TO: no evidence of primary T1: limited to thyroid, 1cm or less T2: limited to thyroid, >1cm but <4cm T3: limited to thyroid >4cm T4: extending beyond capsule,any size Lymph Nodes: NX: cannot be assesssed N0: no regional lymph nodes involved N1: regional node metastases

Metastases: MX: Cannot be assessed MO: no metastases M1: metastases presentStage Under 45 years over 45 YearsI Any T, any N,MO T1, N0, M0II Any T, any N,M1 T2,N0,M0 or

T3,N0,M0III T4,N0,M0 or any

T,N1,M0IV any T,any N, M1

WELL-DIFFERENTIATED THYROID TUMORS

Papillary carcinomaFollicular carcinoma

Because they arise from follicular epithelium and take up radioactive iodine.

PAPILLARY CARCINOMA It tends to occur in young age group (30-

40yrs) and in females. It spreads through lymphatics. Histologically, tumor shows papillary

projections and pale empty nuclei (orphan Annie-eyed).

It is usually bilateral and never encapsulated. It has good prognosis Lateral aberrant thyroid is a metastatic

tumor in cervical lymph node from occult papillary carcinoma.

FOLLICULAR CARCINOMA It is more aggressive than papillary

carcinoma It spreads via blood as it invades capsule and

vessels. Hurthle cells tumor is a variant on

follicular CA, in which tumor contains sheets of eosinophilic cells pacled with mitochondria, which are derived from the oxyphilic cells of the thyroid gland.

- It is different from follicular CA in that they are more often multifocal and bilateral, usually do not take up radioactive iodine, and are more likely to metastasize to local nodes and distant sites and with a higher mortality rate.

TREATMENT OF PAPILLARY AND FOLLICULAR CARCINOMA Post operatively, thyroxine therapy is

avoided for 3 weeks, that leads to elavation of TSH levels (TSH is necessary for uptake of radioactive iodine by residual or metastases of thyroid carcinoma)

Surgical: Total thyroidectomy -If there is clinical involvemnet of

cervical Lymph nodes, then Neck Dissection should also be carried out.

Follow up with thyroglobulin level and whole body thyroid scan

Treat the recurrence or metastasis with

radioactive iodine Life long thyroxine therapy -Thyroxine 200ug, daily ( to provide

replacement of thyroxine and to suppress TSH which can cause recurrence)

PRE-REQUISITES FOR FULL BODY THYROID SCAN It is necessary to ablate all normal thyroid

tissue, or else it will uptake all the radioactive material and residual or metastases will be difficult to detect

TSH levels should be adequate Thyroxine therapy should be stopped for 6

weeks T3 should be given to the patient during this

time period, to decrease the period of hypothyroidism and should be discontinued for 2 weeks before scan to let TSH levels raise.

MEDULLARY CARCINOMA

Arise from parafollicular cells derived from neural crest cells.

Calcitonin and carcinoembryonic antigen is produced by these tumors and can be used as tumor markers

Familial cases occur in children and young adults while sporadic cases occur at any age

It is associated with pheochromocytoma and hyperparathyroidism in MEN-2A mutation.

TREATMENT Total thyroidectomy along with bilateral

central lymph nodes dissection If large tumor or positive central lymph

nodes….modified radical neck dissection Rule out pheochromocytoma by measuring

urinary catecholamine before doing thyroidectomy. If pheochromocytoma present, it should be operated on first

If Hypercalcemia present… only obvious enlarged parathyroid glands should be removed

If normocalcemia…when a normal parathyroid cannot be maintained on a vascular pedicle, it should be removed and then auto transplanted to the forearm.

If RET mutation carriers…Prophylactic

thyroidectomy is indicated - before age of 6 years in MEN2A

patients - before age of 1 years in MEN2B

patients If calcitonin raised and suggests

carcinoma… prophylactic central neck dissection is done.

ANAPLASTIC CARCINOMA More aggressive Treatment : All forms of treatment have dissappointing

outcome If tumor confined to thyroid ( very rare) ,

Then total thyroidectomy should be carried out

External beam radiotherapy has some role If tracheal obstruction present…

isthmusectomy is also done

LYMPHOMA OF THYROID Follows autoimmune thyroiditis (Hashimoto’s

thyroiditis)

Treatment:

Stage I and II … Radiotherapy Stage III and IV…chemotherapy

POST OPERATIVE COMPLICATIONS

Hemorrhage Reespiratory obstruction Tracheomalacia Recurrent laryngeal nerve palsy Thyroid insufficiency Thyrotoxic crisis Hypocalcemia (parathyroid insufficiency) Wound infection Hypertrophic scar or keloid Stitch granuloma

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