Thyroid Swelling (19.3) PDF

Thyroid swelling ‫ﻛوﯾﻰ‬ َ ‫ﺑﺔ َﻟﯾَن ﺻﻼح‬.‫د‬ ‫ﺟراح أﺧﺻﺎﺋﻲ‬ (‫ﺑورد)دﻛﺗوراه‬ FICMS, FICS, MB ChB GENERAL SURGEON The normal thyroid gland is impalpable. The term goiter means generalized enlargement of the thyroid gland. Isolated swelling in one lobe with no palpable abnormality els...

Thyroid swelling ‫ﻛوﯾﻰ‬ َ ‫ﺑﺔ َﻟﯾَن ﺻﻼح‬.‫د‬ ‫ﺟراح أﺧﺻﺎﺋﻲ‬ (‫ﺑورد)دﻛﺗوراه‬ FICMS, FICS, MB ChB GENERAL SURGEON The normal thyroid gland is impalpable. The term goiter means generalized enlargement of the thyroid gland. Isolated swelling in one lobe with no palpable abnormality elsewhere is termed a solitary thyroid swelling. Discrete swelling with evidence of abnormality elsewhere in the gland is termed dominant thyroid swelling Goitre MNG SOLITARY THYROID NODULE Classification of thyroid swellings Simple goitre (euthyroid) Inflammatory Diffuse Autoimmune Multinodular goiter Hashimoto’s disease Granulomatous Toxic goitre De Quervain’s thyroiditis Diffuse(Graves’ disease) Fibrosing Multinodular Riedel’s thyroiditis Toxic adenoma(single) Infective: Acute (bacterial , viral), chronic (TB, syphilitic) Neoplastic Other: Amyloid Benign Malignant Simple goiter Clinical types of simple goiter Diffuse hyperplastic goiter Nodular goiter  Simple goiter Aetiology: This results from excessive stimulation of thyroid gland by TSH , either due to: inappropriate secretion of TSH from a microadenoma in the anterior pituitary (rare) in response to a chronically low level of circulating thyroid hormones due to iodine deficiency or dyshormonogenesis (feed back mechanism)  Iodine deficiency The daily requirement for iodine is about 0.1–0.15 mg. In nearly all districts where simple goitre is endemic there is a very low iodide content in the water and food. Endemic areas are found in the mountainous ranges, such as the Rocky Mountains, the Alps & Himalayas. Although iodides in food and water may be adequate , some time failure of intestinal absorption may Produce iodine deficiency  Dyshormonogenesis Enzyme deficiencies of varying severity may be responsible for many sporadic goiters (i.e. in non-endemic areas) There is often a family history, suggesting a genetic defect.  Goitrogens Vegetables of the brassica family (cabbage, kale) which contain thiocyanate. Note (extra): Mechanism Thiocyanate and thiocyanate-like compounds primarily inhibit the iodine-concentrating mechanism of the thyroid, and their goitrogenic activity can be overcome by iodine administration Thiocyanate at low concentrations inhibits iodide transport by increasing the velocity constant of iodide efflux from the thyroid gland. At high concentrations, the iodide efflux is greatly accelerated, whereas the unidirectional iodide clearance into the gland is inhibited. Thiocyanate at these high concentrations also inhibits the incorporation of iodide into thyroglobulin by competing with iodide at the thyroid peroxidase (TPO) level. Thiocyanate is rapidly converted to sulfate in the thyroid gland. Administration of thyroid-stimulating hormone (TSH) increases the intrathyroidal catabolism of thiocyanate and is capable of reversing the block of iodide uptake produced by this ion. Drugs like, para-aminosalicylic acid (PASA), the anti-thyroid drugs (Thiocyanates & perchlorates) interfere with iodide trapping while carbimazole & thiouracil interfere with the oxidation of iodide & the binding of iodine to tyrosine. Iodides in large quantities Calcium is also goitrogenic Diffuse hyperplastic goitre The goiter appears in childhood in endemic areas but in sporadic cases, it usually occurs at puberty when metabolic demands are high. It is reversible However, it tends to recur later at times of stress such as pregnancy. The goiter is soft, diffuse & may become large enough to cause discomfort. MNG (multinodular goiter) (nodular) Nodules are usually multiple, forming a multinodular goitre Occasionally, only one macroscopic nodule is found, but microscopic changes will be present throughout the gland. Nodules may be colloid or cellular & cystic degeneration, hemorrhage & calcification are common complications. All types of simple goitre are more common in females than males because of the presence of estrogen receptors in thyroid tissue. Nodular goiter – (cut section) This is a cut section of a nodular goiter showing nodules of various sizes with secondary hemorrhage, necrosis and cystic change © Diagnosis Diagnosis is clinical. The patient is euthyroid, The nodules are palpable & visible (smooth, usually firm) & the goitre is painless & moves freely on swallowing A painful nodule or rapid enlargement of a nodule raises suspicion of carcinoma; however, such cases are usually due to hemorrhage into a simple nodule. investigations TFT: (normal T3&T4) with high TSH. TAA: to differentiate it from autoimmune thyroiditis. FNAC: for a dominant thyroid swelling. CXR & XR of thoracic inlet: demonstrate clinically significant tracheal deviation or compression. US & CT: Complications Tracheal obstruction: may occur because of gross lateral displacement or compression by a retrosternal goitre. Acute respiratory obstruction may follow hemorrhage into a nodule impacted in the thoracic inlet. Secondary thyrotoxicosis Follicular Carcinoma Prevention & treatment of simple goitre introduction of iodized salt. Early stages of hyperplastic goitre may regress if thyroxine is given at a dose of 0.15–0.2 mg daily for a few months. Most patients with multinodular goitre are asymptomatic & do not require operation. indications for operations are: 1. pressure symptoms. 2. patient anxiety. 3. Retrosternal extension 4. presence of a dominant area of enlargement that may be neoplastic 5. For cosmetic purpose  Surgical options in MNG 1. Total thyroidectomy: with immediate & lifelong replacement of thyroxine. 2. Subtotal thyroidectomy: involves partial resection of each lobe & leaving up to 8 g of relatively normal tissue in each remnant. 3. Dunhill procedure (near total) total lobectomy of the more affected lobe & subtotal lobectomy of the less affected lobe (solitary Thyroid nodule( Incidence: 3–4% (UK & USA) 3-4 times more frequent in women than men.  Solitary thyroid nodules Malignant 15% Benign 30-40% Papillary (most common) Follicular adenoma Follicular (less common) Medullary & anaplastic (rare) The remainder are due to non-neoplastic conditions like Cyst formation, colloid degeneration with thyroiditis © Index Investigations: TFT: TAA: Ultrasonography Isotope scan (scintigraphy) Indicated when toxicity is associated with nodularity. On scanning, swellings are categorized as hot (overactive), warm (active) or cold (underactive). in hot nodule the surrounding thyroid tissue is inactive ,only the nodule is overacting. A warm nodule takes up isotope, as does the normal thyroid tissue around it. A cold nodule does not take up isotope FNAC The investigation of choice Thyroid conditions that may be diagnosed by FNAC include colloid nodules, thyroiditis, papillary ca., medullary ca., anaplastic carcinoma & lymphoma. FNAC cannot distinguish between follicular adenoma and follicular ca., as this distinction is dependent not on cytology but on histological criteria, which include capsular and vascular invasion  © Index There are very few false positives with respect to malignancy, but there is a definite false-negative rate. US–guided FNAC achieve more accurate sampling. Classification of FNAC reports Thy1 Non-diagnostic Thy2 Non-neoplastic Thy3 Follicular Thy4 Suspicious of malignancy Thy5 Malignant 40 MEDICAL COLLEGE-HMU 21 ،‫ ﺗﺷرﯾن اﻷول‬27 Thy5 FNAC Suppose that it is thy.5 CXR & thoracic inlet XR: CT, MRI: useful in retrosternal & recurrent swellings. PET scan may be useful, particularly in localizing secondaries Laryngoscopy : Flexible laryngoscopy is widely used preop. to determine the mobility of the vocal cords, although usually for medico-legal rather than clinical reasons. The presence of a unilateral cord palsy coexisting with a swelling suggestive of malignancy is usu. diagnostic. Treatment The main indication for operation is the risk of neoplasia. The reason for advocating the removal of all follicular neoplasms (THY.3) is that it is seldom possible to distinguish between a follicular adenoma and a carcinoma except on the basis of histological evidence of capsular or vascular invasion. Indications for operation in thyroid swelling 1.Neoplasia 2.Recurrent cyst Clinical suspicion, including: 3.Toxic adenoma Age 4.Pressure symptoms Male patient 5.Cosmesis Hard texture & irregularity 6.Patient’s wishes Fixity RLN palsy Lymphadenopathy FNAC positive 47 MEDICAL COLLEGE-HMU 21 ،‫ ﺗﺷرﯾن اﻷول‬27