Thyroid nodules are a common issue encountered by surgeons. Epidemiological studies indicate that the incidence is higher in women than in men. Palpation-based detection rates in the general population range from 3% to 7%, while high-resolution ultrasound can detect thyroid nodules in 20% to 76% of randomly selected individuals. Among these, approximately 8% to 16% are thyroid cancers. Accurate differentiation is crucial to avoid missing malignant nodules.
Diagnosis
Medical History
Most patients discover thyroid nodules incidentally during routine examinations. Some patients may present with symptoms, such as the sudden enlargement of a thyroid nodule within a short period, which could suggest hemorrhage due to adenomatous cystic degeneration. Rapid and painless enlargement of a previously existing thyroid nodule in recent days may indicate malignancy.
Particular attention is warranted for thyroid nodules in children and males. Patients with a history of head and neck radiation exposure or a family history of thyroid cancer should be considered at an elevated risk for malignancy.
Clinical Presentation
The majority of thyroid nodules do not exhibit clinical symptoms. When accompanied by thyroid dysfunction, corresponding clinical features may develop. Some patients may experience symptoms caused by the compression of surrounding tissues by the nodule. Features suggestive of malignancy include rapid nodule growth, persistent hoarseness or voice difficulties (in the absence of vocal cord lesions), fixation to surrounding tissues, and pathological enlargement of cervical lymph nodes.
Serological Tests
Thyroid function tests should be performed for all cases of thyroid nodules to determine whether thyroid dysfunction is present. Thyroglobulin levels are not useful for distinguishing between benign and malignant nodules but are generally used to monitor postoperative recurrence in patients with differentiated thyroid cancer. If medullary carcinoma is suspected based on clinical or biopsy findings, serum calcitonin levels should be tested.
Ultrasound Examination
Ultrasound is the preferred initial imaging modality for all thyroid nodules. It provides important information on nodule size, number, location, texture, echogenicity, calcifications, margins, and vascularity. Cervical ultrasound is considered the most important imaging tool for evaluating thyroid nodules. It aids in the differentiation of benign and malignant lesions and assesses for the presence of abnormal cervical lymph nodes.
Radionuclide Imaging
Radionuclide imaging is recommended for thyroid nodules with suppressed serum TSH levels to determine whether the nodule exhibits autonomous uptake. Thyroid autonomous functioning nodules are associated with a low risk of malignancy.
Fine-Needle Aspiration Biopsy (FNA)
Ultrasound-guided fine-needle aspiration biopsy is the preferred pathological diagnostic method before surgery. It can provide a preoperative determination of nodule characteristics, although it has inherent false-positive and false-negative rates. For nodules with inconclusive biopsy results, molecular marker testing (e.g., BRAF mutation analysis) may be performed on biopsy specimens.
Management Principles
Management decisions for thyroid nodules should synthesize information from the medical history, clinical presentation, serological data, and auxiliary test results. For nodules determined to be benign, most cases only require regular follow-up, while surgery is considered for those with clear surgical indications. Fine-needle aspiration biopsy facilitates more accurate treatment planning.
For nodules with suspicious ultrasound findings, negative or indeterminate biopsy results may warrant repeat biopsy or molecular marker testing to improve diagnostic accuracy. Alternatively, periodic surveillance or diagnostic surgery may be considered. Nodules diagnosed as suspicious or malignant on fine-needle aspiration biopsy typically require surgical intervention. In addition to conventional open neck surgery, endoscopic thyroidectomy offers the benefit of relocating the incision away from the neck, resulting in a scar-free cervical area.