Thyroid nodules are a common clinical problem and of concern due to the potential for malignancy, with thyroid cancer diagnoses more than doubling since 1990. While most thyroid nodules are benign, malignancy rates ranging from 3 to 17% have been reported. Histologic evaluation of the thyroid nodule following surgical removal serves as the gold standard for determining malignancy status but, as with any surgical procedure, carries consider able risks. As such, fine-needle aspiration (FNA) biopsy has become standard practice for initial evaluation and diagnosis of thyroid nodules, reducing the number of surgeries performed to remove thyroid nodules.
Although FNA is well-accepted and widely used for the diagnosis of thyroid nodules, the current literature presents conflicting evidence regarding the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FNA biopsy compared to histologic examination of a surgical specimen to accurately predict malignancy status in large (4 cm in diameter) thyroid nodules.
Some studies have shown that FNA performs poorly in larger nodules and, as such, some medical centers have opted to remove nodules 4 cm, even if biopsy findings are benign. This recommendation can be
troublesome for some patients with large nodules, especially those have reduced life expectancies due to age or co-morbidities or for whom surgery may represent a significant health risk or financial hardship. We hypothesize that patients with thyroid nodules 4 cm who test negative for malignancy by ultrasound-guided FNA do not automatically require surgical resection. The purpose of this study was to provide clinicians with practical data regarding the accuracy of FNA for detecting malignancy in large thyroid nodules and discuss the utility of FNA for guiding surgical decisions.
Thyroid nodules are very common, with reported prevalence rates as high as 68% in the general population. Thyroid FNA biopsy is an effective tool for diagnosing thyroid nodules; however, there is considerable controversy regarding the ability of FNA to detect malignancy in nodules 4 cm. Due to this controversy and the poor prognosis of malignant nodules 4 cm in diameter, some centers recommend that all nodules over this. Cutoff be surgically removed regardless of biopsy findings. While surgery is clearly indicated in many cases, the decision to operate should not be taken lightly. Thyroid surgery
is challenging and can have serious complications. The extent of surgery and the experience of the surgeon both play important roles in determining the risk of surgical complications, with total thyroidectomy carrying higher risk than unilateral lobectomy. Reduction in quality of life after surgery is multifactorial and may include the need for lifelong medication, hypoparathyroidism, dysphagia,
and dysphonia, which may be temporary or permanent.
In addition, bilateral recurrent laryngeal nerve paralysis is a rare but life-threatening complication of total thyroidectomy, requiring tracheostomy placement to maintain patent airway. Although
hypoparathyroidism is not a typical complication of lobectomy, some patients can develop mild to moderate hypocalcemia, which is usually transient after unilateral thyroid lobectomy.
Surgical complications occur relatively frequently. Approximately 1 in 10 patients experience temporary laryngeal nerve injury after surgery, with longer lasting voice problems in up to 1 in
25 . The rate of postoperative hypoparathyroidism is harder to estimate, because published studies have used different criteria to define its presence. A study by Asari et al reported rates ranging from
1.6 to 50% , with the rate of hypoparathyroidism in experienced centers likely to be lower. Given these risks and the remaining controversy surrounding malignancy risk in large thyroid nodules, we believe providers should consider observation instead of automatically proceeding to surgery, especially if cancer prevalence and NPV are known. In cases where surgical risk is unclear, it may be beneficial to consult with a surgeon who may be able to offer insight regarding how difficult it will be to perform a lobectomy or thyroidectomy. Conversely, the decision to not remove a nodule should be evaluated carefully. Size is a very important prognostic factor in thyroid cancer.
Patients with thyroid nodules are candidates for USG-FNA. However, palpable ··nodules” are not always
true nodules by US in up to 30 % of patients, and a palpable “not nodular·· thyroid gland may have a small and/or posterior nodule that may not be palpable. but may be amenable to USG-FNA. When abnormal lymph node are present,suspected thyroid nodules. goiter, and palpable thyroid nodule(s) or have risk factors for malignancy should undergo US examination of the thyroid gland and soft tissue of the neck, in
addition to a complete clinical history. Physical examination mainly of the head and neck and serum levels of thyroid-stimulating hormone (TSH).Patients with normal or high TSH levels and US-visible nodule(s)
may be candidates for USG-FNA. Patients with lowTSH levels and US-visible nodule(s) should
have a radionuclide thyroid scan. A functioning nodule often does not need to undergo FNA, because the possibilites of malignancy is rare USG-FNA of the lymph node for cytology and thyroglobulin (TG) levels in needle rinses should be performed at the time of USG-FNA of the thyroid nodule.