Tumors of the thyroid-Tutorial 5(0).pptx

Power point presentation on tumors of the thyroid

1. TUMORS OF THE THYROID

2. OUTLINE INTRODUCTION ANATOMY AND PHYSIOLOGY ETIOLOGY CLASSIFICATION BENIGN, MALIGNANT HISTORY PHYSICAL EXAMINATION INVESTIGATIONS MANAGEMENT

3. OBJECTIVES Know the different pathological types and their behaviour Diagnose a patient with thyroid tumours Use appropriate investigations Select appropriate management of thyroid tumours

4. INTRODUCTION The annual incidence of thyroid neoplasms are about 3.7 per 100 000 of the population. Benign tumours more common about 90% of cases Malignant neoplasm of the thyroid is uncommon and with a world incidence of 40 per million accounting for less than I% of all malignancies. It is seen from childhood to old age with a peak incidence in the 6th decade in Europe and America but in the 4th in Africa Sex ratio is three females to one male. Six per million die from it yearly. Fourtunately , the most common of these (papillary and follicular) are also the most curable.

5. ANATOMY OF THE THYROID GLAND

6. ETIOLOGY Irradiation Hereditary Thyroid stimulating hormone Hashimoto thyroiditis may predispose to NHL/papillary carcinoma of thyroid Pre-existing multinodular goiter may turn into follicular carcinoma of thyroid Nearness to volcanoes

7. CLASSIFICATION OF THYROID NEOPLASMS A) BENIGN 1. Adenoma a) Follicular i ) Colloid variant ii) Embryonal iii) Fetal iv) Hurthle cell variant b) Papillary c) Atypical 2. Teratoma B) MALIGNANT( DUNHILL CLASSIFICATION ) 1) DIFFERENTIATED -Papillary carcinoma (60%) -Follicular carcinima (20%) - Papillofollicular carcinoma - Hurthle carcinoma 2) UNDIFFERENTIATED -Anaplastic carcinoma (10%) 3) Medullary carcinoma (5%) 4) Malignant lymphoma (5%) 5) Secondaries in thyroid( rare) from kidney,colon,melanoma

8. ADENOMA Adenoma of the thyroid originates from the follicular epithelium (occasionally Hurthle cell) and is predominantly follicular. Follicular adenoma histologically has an appearance similar to that of nodular goitre and the cell types are colloid variant (microfollicular), Hurthle and fetal (macro follicular). It is a solitary swelling which may be over 10cm in diameter and is encapsulated Occasionally,micro invasion will be seen suggesting a malignant change.

9. ADENOMA It may be functional and 'hot' or non-functional and 'cold' when malignancy may be suspected. It may become hyperplastic and cause secondary thyrotoxicosis. It is more common in females and clinically the swelling is firm and movable within the thyroid. It is important to distinguish the lesion from a malignant neoplasm by appropriate investigations.

10. PAPILLARY THYROID ADENOCARCINOMA The most common thyroid maligancy(70-80%) and is usually associated with an excellent prognosis, particularly in young females It accounts for most cases in children and has the highest incidence in the 3rd and 4th decades. The most important risk factor is childhood exposure to radiation. It is slow growing and remains localized for a long time and metastasizes late to the cervical and upper mediastinal lymph nodes.

11. PAPILLARY THYROID ADENOCARCINOMA Histologically the tumour shows papillary projections and characteristic pale, empty nuclei (Orphan Annie-eyed nuclei) . Papillary carcinomas are very seldom encapsulated. There is microscopic intraglandular spread to the contralateral lobe in 90% of cases and 7% may grow if the lobe is not resected They may be due to lymphatic spread in the rich intrathyroidal lymph plexus. Spread to the lymph nodes is common, but blood-borne metastases are unusual.

12. PAPILLARY THYROID ADENOCARCINOMA There are several variants of adenocarcinoma • Papillary adenocarcarcinoma : which is small and may be a sclerotic encapsulated nodule. • Encapsulated variant : with a capsule like an adenoma though there is local invasion. • Folicular variant: with predominance of follicles over papillae though the metastases show mainly papillae. • Diffuse sclerosing variants: mainly in children which is infiltrated with lymphocytes, very aggressive and with poor prognosis. • Tall papillary variant: seen in the eldely and very aggressive with poor prognosis.

13. Histology of papillary thyroid carcinoma showing typical papillary projections and empty (Orphan Annie-eyed) nuclei

14. FOLLICULAR THYROID ADENOCARCINOMA It is still commoner in the iodine deficient developing countries compared to the developed countries despite the relative decrease in its frequency . The highest incidence is in the 5th decade. It is slow- growing and osleolytic . They appear to be macroscopically encapsulated but, microscopically, there is invasion of the capsule and of the vascular spaces in the capsular region. lymph node involvement is much less common than in papillary carcinoma. Blood-borne metastases are more common and the eventual mortality rate is twice that of papillary carcinoma.

15. MEDULLARY THYROID CARCINOMA It is an apudoma and arises from the para follicular C-cells which originate from the neural crest and secrete calcitonin. lt may be sporadic(75 %) when only one lobe is usually affected or as part of the familial syndrome MEN Ila, MEN IIb or non MEN familial MTC (25%) when the tumour is multicentric and both lobes are usually affected. It starts as a generalized C-cell hyperplasia followed by the development of tumour . Excess secretion of calcitonin has been shown to be effective marker for the presence of MTC and the presence of a mass and an elevated calcitonin level is virtually diagnostic of MTC. It presents between 50-70 but when familial, before 30. Diarrhoea is a feature in 30 per cent of cases It spreads usually by lymphatics but also by blood vessels.

16. UNDIFFERENTIATED(anaplastic) CARCINOMA It accounts for about 5 -10% .This occurs mainly in elderly women. It is hard, rapidly growing and consists of sheets of undifferentiated small or giant cells. Although it may arise de novo, it is often associated with a concurrent differentiated thyroid cancer. It is iniatiated by mutation in the RAS proto-oncogene. The typical presentation is an elderly patient with dyspahgia ,cervical tenderness and a painful ,rapidly enlarging neck mass. ical manifestatiging neck mass. They are extremely lethal tumours and survival is calculated in months. Complete resection is justified if the disease appears confined to the thyroid. Even then the survival is barely 6 months. It is radio-sensitive.

17. LYMPHOMA Thyroid lymphomas are almost all non-Hodgkin lymphomas and most are B cell in origin . A subgroup of mucosa associated lymphoid tissue(MALT) lymphomas occur in 6%-27% of patinets. The risk is increased by 70 fold by hashimoto thyroiditis which often leads to hypothyroidism and so to increased TSH production. The diagnosis is considered in patients with a goiter especially one that has apparently grown significantly in a short period.

18. Tumour –node–metastasis (TNM) staging of thyroid cancer. Tumour TX Primary cannot be assessed T0 No evidence of primary T1 Tumour ≤2 cm T1a: ≤1 cm T1b: >1 cm ≤2 cm T2 Limited to thyroid, >2 cm but ≤4 cm T3 Limited to thyroid, >4 cm or any tumour with minimal extrathyroid extension T4 Any size with extensive extra thyroidal extension T4a: moderately advanced T4b: very advanced Nodes NX Cannot be assessed N0 No regional node metastases N1 Regional node metastases N1a: level VI N1b: any/all other levels Metastases MX Cannot be assessed M0 No metastases M1 Metastases present

19. Current Staging System Stage Under 45 years Over 45 years I Any T, any N, M0 T1, N0, M0 II Any T, any N, M1 T2, N0, M0 III T3 or T1, T2 and N1a M0 IVA T4 or T1,T2,T3, T4a and N1b M0 IVB T4b Any N M0 IVC Any T Any N M1

20. HISTORY 1. A swelling of the thyroid which may have been present for some years or is of recent onset, painful. It may be solitary or multinodular 2. Dyspnoea from pressure on the trachea, hoarseness of voice from infiltration of the recurrent laryngeal nerve, dysphagia from infiltrative pressure of the oesophagus, pain in the ear from infiltration of the vagus nerve. Rarely, there may be Horner's syndrome from involvement of the cervical sympathetic chain 3. Swellings of the neck from secondary deposits in the cervical lymph nodes without obvious swelling of the thyroid 4. Pathological fracture of a long bone or spine or as a pulsating bone tumour especially in the skull 5. There may be a family history of thyroid cancer or exposure of the head and neck to irradiation. 6. General malaise amd weight loss

21. HISTORY Type of neoplasm Age Sex Symptoms Duration of symptoms Cause Papillary Adenocarcinoma Is a tumour of children and young adults. Females are affected three to four times more often than males. The common presenting symptom is a lump in the neck in the region of the thyroid. The lump may be present for many years. It is slow growing. Exposure of radiation to the neck and mediastinum. Follicular Thyroid carcinoma Occurs in adults, with the highest incidence at 50 years. Females are more affected than males. The common presenting symptom is a lump in the neck in the region of the thyroid. The lump may be present for many years. It is slow growing. 1.Exposure of radiation to the neck and mediastinum. 2.iodine deficiency. Anaplastic Carcinoma Occurs between the ages of 60 and 80 years. Females are more affected than males. 1. A lump in The neck. 2. Hoareness 3. Dypnoea 4. Pain the ear The lump is present for a few years. The tumour grows rapiudly. 1.Iodine deficiency. Medullary Thyriod Cercinoma Most occur between 40 and 70 years. Patients with a family history, 20-30years. Same incidence rate in males and females. 1. A lump in the neck. 2. neuromas of the tongue, lips and conjuctivae . 3. diarrhea Depends on the age of the patient. Ask for a family history of mutiple endocrine neoplasia(MEN)

22. PHYSICAL EXAMINATION 1. The swelling may be a single nodule which is firm and movable within the thyroid, or hard and fixed 2. The whole gland may be irregularly enlarged or multinodular, hard and craggy with or without some fixity to trachea and surrounding tissues 3. The cervical lymph nodes may be enlarged, firm and mobile or hard and fixed. The cervical nodes may be enlarged without an obvious swelling of the thyroid

23. INVESTIGATIONS 1. Laryngoscopy. All patients suspected of thyroid neoplasm must have their larynx examined to determine or rule out (i) Cord paralysis or paresis due to recurrent laryngeal nerve involvement (ii) Laryngeal infiltration (iii) Laryngeal pathology. Hoarseness in a goitrous patient may be due to papilloma of the vocal cord.

24. 2. Radiology of the neck, thoracic inlet, lungs and bones suspected of deposits. There may be fine stippled calcification in the tumour suggestive of psammoma bodies of papillary adenocarcinoma. Displacement and narrowing of the trachea and, very rarely, carcinomatous infiltration of the trachea may be detected. Secondary deposits in the lungs and skeleton may also be detected.

25. 3. Isotope Scan The swelling may be 'cold‘ 50% of 'cold' solitary swellings are simple multi-nodular goitre , the other nodules being clinically impalpable Of the remaining 50%, only about 12 % are malignant However, a 'cold' nodule is a strong indication for urgent surgery as it may be malignant 2% of well-differentiated tumours take up the isotope. The liver, bones and lungs are also scanned for metastases Isotope imaging with pentavalent Technetium 99m dimercaptosuccinic acid (99mTc (V) DMSA) or Iodine131 meta- iodo benzylguanidine (131 IMIBG) is used to determine the extent of local disease and monitor recurrence after surgery

26. 4. Fine needle aspiration cytology (FNAC) It is useful in diagnosing papillary, medullary and anaplastic carcinoma There is a small risk of false-negative results It is difficult to differentiate between simple and malignant follicular tumours by FNAC

27. 5. Serum thyroglobulin/calcitonin The serum thyroglobulin in papillary or follicular cancer and serum calcitonin ( basaI or stimulated) in medullary cancer are elevated They fall after complete removal of the tumour Elevation later indicates recurrence In suspected MTC in MEN II, basal and pentagastrin -stimulated serum calcitonin are elevated and DNA analysis for mutation of RET on Cr 10 is diagnostic Nb: the gene associated with MEN II is called RET The immediate family of the patient is screened for MTC 6. In MTC, investigations for MEN should be done. In particular, pheochromocytoma should be ruled out to avoid a possible crisis during operation

28. MANAGEMENT 1. Surgery • Total thyroidectomy • Near total (leaving a rim of tissue posteriorly to protect the parathyroids) • If lymph nodes are affected, the regional lymph nodes should be cleared • Prophylactic thyroidectomy in MTC, positive family members since MTC does not respond to radiation or chemotherapy . 2. Radiotherapy • Anaplastic tumours and lymphomas are irradiated with external beam radiation whether surgery is possible or not. • Inoperable differentiated tumours and lymph node metastases are also irradiated.

29. 3. Chemotherapy In lymphoma, cyclophosphamide, doxorubicin, vincristine and prednisolone are given after external beam radiation In anaplastic carcinoma doxorubicin may be given 4. Radioactive iodine Adjunct to surgery in papillary and follicular tumours and also for micrometastases 5. Inhibition of TSH Follicular and papillary tumours are TSH dependant So thyroxine O.3g/day is given to inhibit TSH release and also as a replacement therapy

30. PROGNOSIS Depends on the pathological type, age and sex of the patient; Better ˂ 40 yr Better in females Increasing size (> 3cm) Grade of the tumour, extrathyroidal involvement Distant metastases

31. PROGNOSIS Papillary Adenocarcinoma Has the best prognosis, 84 %, 63 % and 60% being alive at 5, 20and 30years respectively Follicular Thyroid Adenocarcinoma Nearly 60% and 40% are alive at 5 and 30 years respectively Anaplastic Carcinoma Has a very poor prognosis, most patients being dead within a year and very few at 3 years Medullary Thyroid Carcinoma. 50% of patients are dead by 10 years. In sporadic MTC, 55 % are alive at 10 years

32. REFERENCES Bailey and Love’s short practice of surgery. 26th edition BAJA’s Principles and Practice of Surgery. Browse’s Introduction to the Symptoms and Signs of Surgical Disease. Medscape

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