ED: Thyroid nodules can be a source of anxiety for patients and doctors. Managing the thyroid nodule has changed little, but imaging and cytopathology have become much more sophisticated.
The prevalence of palpable thyroid nodules is 5% in women and 1% in men. With the ease of access to high-resolution ultrasound scans, 19%-68% of randomly selected people have a thyroid nodule and importantly, 7-15% of nodules will be thyroid cancer, ranking this cancer 3rd amongst females (12%) and 4th amongst males (7%) within the 15-39 age group (2014 WA Cancer Registry).
Surgical indications are known cancer or suspicion thereof, compressive goitre or retrosternal goitre, or thyrotoxicosis. Clinical assessment with ultrasound and cytopathology determines whether to recommend surgery or medical management.
Assessment is multimodal (clinical/sonography/cytology)
Clinical presentation can be asymptomatic e.g. incidental nodule on imaging. Symptomatic presentations include neck mass, hoarseness, airway difficulty, chronic cough, dysphagia, persistent sore throat, Pemberton’s sign (facial engorgement on raising upper limbs) or venous neck distension. Most thyroid cancers occur sporadically, however enquiry into risk factors (including radiation exposure or family history of thyroid cancer) is useful.
Red flags for referral to a surgeon include stridor associated with a goitre, nodules in patients with risk factors for thyroid cancer, unexplained hoarseness, rapid and painless enlargement over weeks, cervical lymphadenopathy, or tethering or fixity of a neck mass.
The American Thyroid Association (ATA) guidelines for managing thyroid nodules are largely accepted here and determine who should have fine needle aspiration cytology (FNAC). For instance, ATA High and Intermediate suspicion nodules should have FNA at ≥1 cm; ATA Low suspicion should have FNA ≥1.5 cm; and ATA Very Low suspicion should have FNAC ≥2 cm. ATA Benign (pure cyst) or nodules <1 cm probably do not need FNAC.
Cytological stratification
The Bethesda system of nodule classification is common.
Bethesda III and IV nodules represent indeterminate group- follicular lesions, some of which will be follicular cancers. It is not possible to diagnose Follicular Cancer on cytology alone as vascular and capsular invasion are diagnostic hallmarks.
Other tests for working up a nodule include TFT and TPO. If thyrotoxicosis is present adding fT3, tF4, TSHR Ab, and a thyroid scan will help. For patients who are potentially in need of thyroid surgery, adding PTH and Calcium to exclude concomitant primary hyperparathyroidism is beneficial as two birds can be got with one stone.
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