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Epidemiology and Clinical Manifestations
Thyroid nodules are common in clinical practice and, although the majority are benign, approximately 5% can harbor malignancy. Their prevalence is highly dependent on the method used for detection. With the increased utilization of ultrasound (US) for evaluation of non-thyroid lesions of the neck, the incidental finding of unsuspected thyroid nodules (‘incidentalomas’) has dramatically increased. The prevalence of thyroid nodules increases with advancing age and is higher in women. However, thyroid nodules are more likely to be malignant in men, patients with a history of head and neck irradiation, children, and young or older adults (<30 or >60 years of age).1
The evaluation of a patient with a palpable solitary nodule is generally straightforward and usually will include a fine-needle aspiration (FNA) biopsy with or without US guidance. It is important to recognize that in up to 50% of patients with a clinically palpable solitary nodule, ultrasonography will often demonstrate the presence of one or more additional nodules.2 The evaluation and management of patients with multinodular goiters (MNGs) represents a much more difficult problem in the clinical setting. Non-palpable nodules have the same risk for malignancy as palpable nodules of a similar size.3 Although it has been generally postulated that the risk for thyroid cancer is lower in patients with MNG compared with patients with solitary nodules, some studies have shown a similar incidence of cancer in both groups.4,5
The clinical manifestations of patients with MNGs are variable and to a great extent depend on the size and location of the goiter and whether the nodules are hyperfunctioning or not. Many patients with MNGs can be completely asymptomatic, particularly when the goiter is small and the functional status of the thyroid is normal. Other patients may present with a visible goiter that may have been present for years in the absence of other clinical symptoms. However, in some patients thyroid growth may occur in the thoracic cavity (substernal goiters) and result in obstruction or pressure of any of the structures within the cavity. Tracheal compression can result in dyspnea, which is most commonly exertional but can be positional;6,7 dysphagia or hoarseness from compression of recurrent laryngeal nerve are other symptoms that may be seen in patients with large goiters. Hyperthyroidism, either overt or subclinical, may be present in up to 25% of patients with MNG.8