الفهرس 
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Abstract
Thyroid nodule is a discrete lesion in the thyroid gland that is radiologically distinct from the surrounding thyroid parenchyma.
Thyroid nodules are a common presentation in the clinic, with an increasing incidence, especially in women. The detection rate among healthy individuals is as high as 50%‐60%, but the reported incidence of malignant nodules in all thyroid nodules has ranged from only 1.6%‐12%.
They are discovered either clinically on self-palpation by a patient, or during a physical examination by the clinician or incidentally during a radiologic procedure such as ultrasonography (US) imaging, computed tomography (CT) or magnetic resonance imaging (MRI) of the neck; with the increased use of sensitive imaging techniques, thyroid nodules are being diagnosed incidentally with increasing frequency in the recent years.
Though thyroid nodules are common, their clinical significance is mainly related to excluding malignancy (4.0 to 6.5% of all thyroid nodules), evaluating their functional status and if they cause pressure symptoms.
Thyroid nodules can be caused by many disorders: Benign (colloid nodule, Hashimoto’s thyroiditis, simple or hemorrhagic cyst, follicular adenoma and subacute thyroiditis) and malignant (Papillary Cancer, Follicular Cancer, Hurthle Cell Cancer, Anaplastic Cancer, Medullary Cancer, Thyroid Lymphoma and metastases).
Initial assessment of a patient found to have a thyroid nodule either clinically or incidentally should include a detailed and relevant history plus physical examination. Laboratory tests should begin with measurement of serum thyroid-stimulating hormone (TSH). Thyroid scintigraphy/radionuclide thyroid scan should be performed in patients presenting with a low serum TSH.
Thyroid ultrasound should be performed in all those suspected or known to have a nodule to confirm the presence of a nodule, evaluate for additional nodules and cervical lymph nodes and assess for suspicious sonographic features.