Incidental thyroid nodules
C L I N I C
A
U P D A T E
L
(1) Benign. There is a <5% chance of malignancy. Most would recommend a repeat ultrasound in 6-12 months looking for nodule growth (>20% increase in 2+ dimensions) prompting another biopsy. Follow up from here onwards is contentious and can be by palpation or serial ultrasound.
By Dr Brett Sillars, Endocrinologist
hyroid nodules are a common incidental finding when performing neck imaging for another indication. The prevalence of thyroid nodules increases with advancing age and are found in over 50% of individuals at autopsy. Around 5% of thyroid nodules prove to be malignant. It is therefore not surprising that the incidence of thyroid cancer is rising due to the increased detection of small papillary thyroid cancers. Despite this increase, mortality from thyroid cancer remains similar, reflecting the rather indolent nature of these small cancers. The investigation and management of thyroid nodules can be challenging.
T
Initial investigation Investigation of a thyroid nodule(s) involves: (1) TSH; (2) Dedicated thyroid ultrasound: to confirm nodule, imaging characteristics, size, detect other nodules and lymphadenopathy; (3) Thyroid nuclear medicine scan. If the TSH is suppressed (<0.1 mU/L), thyroid scintigraphy should be performed as the nodule may be hyperfunctioning or “hot”. These have a low malignant potential and biopsy is rarely indicated. Consider an endocrinology referral for review and potential I131 therapy.
When to do a fine needle aspiration The decision to FNA is dependent on patient history (family history of thyroid cancer, previous neck irradiation, voice change), ultrasound characteristics and nodule size. High risk features on ultrasound include microcalcifications, hypoechogenicity, internal
vascularity, tall > wide, irregular margins and lymphadenopathy. Biopsy should be considered in most nodules greater than 1-1.5cm, however smaller nodules (>5mm) that display high risk ultrasound features should be considered for biopsy. Biopsy is not indicated for entirely cystic nodules. Fine needle aspiration is a very safe procedure and is generally performed under ultrasound guidance to improve diagnostic yield. Deciding which nodules to FNA in a multinodular thyroid can be difficult. Cancer within a multinodular thyroid is present in the largest nodule only 50% of the time. Generally speaking, those nodules with high risk ultrasound features should be preferentially biopsied.
Cytology results and follow-up Cytology reports from an FNA should fall within the following categories to guide further management.
(2) Malignant papillary cancer or (3) Suspicious for papillary cancer. Refer to thyroid surgeon. 4) Indeterminate (Atypical/Hürthle cell/ Follicular neoplasm). There is a 25% overall risk of malignancy within this group. Refer to thyroid surgeon. 5) Inadequate. Insufficient material to make a diagnosis. Repeat FNA is advised. Recommended resource: http://www. thyroidguidelines.org/revised/taskforce
n Figure 1: Ultrasound of incidentally found hypo-
echoic thyroid nodules. The smaller (marked) nodule with ill-defined margins had an indeterminate FNA and was subsequently diagnosed as papillary thyroid cancer. The larger nodule was benign.
6,329 MATTERS OF THE H RT Each year, we deliver amazing CARDIOLOGY care to WA www.oneramsay.com.au 38
ATTADALE
Private Hospital
GLENGARRY Private Hospital
HOLLYWOOD Private Hospital
JOONDALUP Health Campus
medicalforum