+++
ESSENTIALS OF DIAGNOSIS
++
ESSENTIALS OF DIAGNOSIS
Single or multiple thyroid nodules are commonly palpated by the patient or clinician or discovered incidentally on imaging studies.
Thyroid function tests recommended.
FNA cytology for thyroid nodules ≥ 1 cm or for smaller nodules when prior head-neck or chest-shoulder radiation.
Ultrasound guidance improves FNA diagnosis for palpable and nonpalpable nodules.
Clinical follow-up required.
+++
GENERAL CONSIDERATIONS
++
Thyroid nodules are common. Palpable nodules occur in 4–7% of adults, and most are at least 1 cm in diameter. They are more common in women than men and become more prevalent with age. Most patients with a thyroid nodule are euthyroid; however, there is a high incidence of hypo- or hyperthyroidism. Patients with palpable nodules require thyroid function testing and evaluation for thyroid malignancy.
++
Thyroid nodules may be detected incidentally on imaging done for another purpose. The prevalence of incidental thyroid nodules depends upon the imaging modality: MRI, 50%; ultrasound, 30%; CT, 13%; 18FDG-PET, 2%. When such scans detect a nodule, a thyroid ultrasound is performed to help determine the risk for malignancy and to establish a baseline for follow-up examinations. Most nodules that are 1 cm or more in diameter require fine needle aspiration cytology (FNAc). Smaller nodules may be selected for FNAc if their ultrasound appearance is suspicious for malignancy or if they arise in a patient who has an increased risk for thyroid malignancy.
++
The overall risk of malignancy (ROM) for thyroid nodules 1 cm or larger in diameter is lower than previously thought due to the large number of incidentally discovered benign nodules that require evaluation. In a large prospective German study of thyroid nodules, the ROM was 1.2% overall and 2.8% in patients under age 30 (excluding papillary microfollicular carcinoma). The risk of a thyroid nodule being malignant is higher in (1) men; (2) patients with a history of head-neck radiation or exposure to radioactive fallout as a child; (3) patients with a personal history of malignancy; (4) patients with a family history of thyroid cancer or a thyroid cancer syndrome, such as multiple endocrine neoplasia type 2, familial polyposis, Carney syndrome, or Cowden syndrome; (5) large solitary nodules; and (6) hoarseness, vocal fold paralysis, adherence to the trachea or strap muscles, or cervical lymphadenopathy.
++
Table 28–6 illustrates how to evaluate thyroid nodules based on the index of suspicion for malignancy.
++