Thyroid nodules

The impact of thyroid nodule size on the risk of malignancy and accuracy of fine-needle aspiration: a 10-year study from a single institution

BACKGROUND

False-negative rates for thyroid fine-needle aspiration (FNA) vary from 0.4% to 13%, but the effect of nodule size on the accuracy of thyroid FNA remains controversial. We hypothesized that large thyroid nodule size does not contribute to the risk of malignancy or the risk of a false-negative FNA.

METHODS

All thyroid FNAs performed at the Walter Reed Army Medical Center during September 2001-August 2011 were reviewed. A strict correlation between the biopsy site, location, and size of nodule on ultrasound (US) and pathology report was ensured. FNA results were classified as benign, atypical, follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), suspicious for malignancy (SM), or malignant, and the pathology result was categorized as either benign or malignant. Nodules were analyzed by size: 0.5-0.9 cm (group A), 1.0-3.9 cm (group B), and ≥ 4 cm (group C). Incidental thyroid cancer was not included.

RESULTS

Of 3013 patients undergoing FNA, 667 (22.1%) had surgery. Patients were excluded for nodules <0.5 cm, nondiagnostic FNA, or no preoperative US, leaving 540 patients with 695 nodules. Among patients referred for surgery, FNA results were benign in 417 nodules (60%), atypical in 22 (3.2%), FN/SFN in 122 (17.6%), SM in 77 (11.1%), and malignant in 57 (8.2%). Postoperative malignancy rates by FNA result were 7% if benign, 4.5% if atypical, 23% if FN/SFN, 33.8% if SM, and 78.9% if malignant. FNA accuracy was 60% in group A, 68.5% in group B, and 80.3% in group C (p=0.01). False-negative rates for FNA were 7.0% overall, 15.8% in group A, 6.3% in group B, and 7.1% in group C (p=0.25). Sensitivity and negative predictive value were highest in group B at 81.6% and 93.7%, respectively. The prevalence of malignancy was not different between groups.

CONCLUSION

Our results show that the thyroid nodule size ≥ 4 cm increases neither the risk of false-negative FNA results, nor the overall risk of malignancy. We also show a tendency toward a higher false-negative rate in subcentimeter nodules. We conclude that a large nodule size should not prompt automatic referral for thyroidectomy. An increased awareness of potential sampling error in subcentimeter nodules is warranted.

Reliability of fine-needle aspiration for thyroid nodules greater than or equal to 4 cm

BACKGROUND

Fine-needle aspiration (FNA) is considered the diagnostic test of choice in the evaluation of thyroid nodules. Some practice recommendations, however, suggest surgical resection of larger thyroid nodules due to concerns of FNA unreliability in the diagnosis of thyroid malignancy. The purpose of this study was to determine the reliability of FNA in thyroid nodules ≥4 cm.

METHODS

Retrospective review of prospectively collected data of 1068 consecutive patients who underwent FNA and thyroidectomy at a single tertiary medical center from 2003 to 2010 was performed. Patients were divided into two groups: those patients with a dominant thyroid nodule ≥4 cm (n = 212) and those patients with a dominant thyroid nodule <4 cm (n = 856). Sensitivity, specificity, and negative and positive predictive values were calculated for FNA results and final histopathology after thyroidectomy.

RESULTS

Of 212 patients with lesions ≥4 cm, 35% had thyroid malignancy on final pathology. Conversely, 54% of 856 patients with dominant thyroid nodules <4 cm had a final diagnosis of thyroid cancer after thyroidectomy. FNA demonstrated similar test characteristics among patients with lesions ≥4 cm and <4 cm, with a specificity of 99% (CI: 96%-100%) and 98% (CI: 96%-99.0%), respectively, and a sensitivity of 35% (CI: 23%-49%) and 42% (CI: 37%-46%), respectively. The positive predictive value of FNA was 82% (CI: 75%-100%) for nodules ≥4 cm and 96% (CI: 92%-98%) for nodules <4 cm. Negative predictive value was significantly different, with a value of 82% (CI: 75%-87%) for lesions ≥4 cm and only 59% (CI: 55%-63%) for lesions <4 cm.

CONCLUSIONS

The reliability of FNA as a diagnostic test is not affected by the size of thyroid nodules. Routine surgical resection for all thyroid nodules ≥4 cm should not be used as the only independent factor in determining need for surgical resection.

Is it useful to routinely biopsy hot nodules in iodine deficient areas?

Incidence of nodular thyroid disease as well as that of functioning thyroid nodules (FTN) increases dramatically in iodine deficient (ID) areas. Cancer is extremely rare in FTN; thus, some do not routinely biopsy and treat them with radioactive iodine (RAI) straight away or follow-up. The outcome of 296 patients followed or treated at our institution for solitary or multiple FTN were retrospectively evaluated. Hospital records of 224 female, 72 male patients, with a mean +/- SD age of 54.9 +/- 12.4 yr and followed for 22 (0-156) months were examined. 175 patients had solitary, 121 had multiple hot or warm nodules. 230 (77.7%) of the patients received RAI treatment. 402 fine needle aspiration biopsies (FNABs) were performed on 260 patients and on 343 FTN (381 benign and 21 suspicious diagnoses). Eleven of the patients were operated for suspicious FNAB results and 10 were followed-up. Only one nodule turned out to be malignant. Malignancy is extremely rare in functioning thyroid nodules (0.34%) and some of malignant cases could be predicted by their suspicious clinical features. Routine practice of treating FTN with RAI therapy is reasonable in clinically low-risk patients. FNAB is reserved for cases with suspicious clinical features, resulting in fewer surgeries and reduced cost.

Use of fine-needle aspiration cytology and frozen section in the management of nodular goiters

BACKGROUND

This study evaluates the role of frozen section (FS) in surgical decisions for nodular thyroid disease when a preoperative fine-needle aspiration cytology (FNAC) is available.

MATERIAL AND METHOD

The charts of 113 patients who underwent thyroidectomy for nodular goiter were reviewed. Each patient underwent FNAC, FS, or both. Results were compared with the final pathologic examination to evaluate their effectiveness in predicting malignancy.

RESULTS

The sensitivity and specificity of FNAC alone (49 patients) were 73% and 93.5%, respectively, and of FS (111 patients) 68% and 99%, respectively. The result of fine-needle aspiration cytology was: benign (n = 8), malignant (n = 13), indeterminate (n = 25), and nondiagnostic (n = 3). All cases diagnosed as benign on FNAC were benign on final pathology, but of the six FS performed in these cases, four were benign and two were suspect. Of the 13 FNAC that were interpreted as malignant, 11 and 10 proved to be malignant on final pathology and FS, respectively. The 25 indeterminate cases on FNAC were on final pathology benign (n = 21) and malignant (n = 4) and on frozen section were benign (n = 12), malignant (n = 2), and suspect (n = 11).

CONCLUSION

When results of FNAC are interpreted as benign or malignant, FS is of little value, because it does not change the extension of thyroidectomy. FS proved useful in determining the extent of thyroidectomy only when results of the FNAC were suspect or atypical.

User of fine-needle aspiration biopsy and frozen section in the management of the solitary thyroid nodule

BACKGROUND

This study evaluates the indication for frozen section (FSx) in the management of the solitary thyroid nodule given the increasing use of fine-needle aspiration biopsy (FNAB).

METHODS

The charts of 561 patients who underwent thyroidectomy for a solitary nodule were reviewed. Each patient underwent either FNAB, FSx, or both. Results were compared to the final diagnosis to evaluate their effectiveness in predicting malignancy.

RESULTS

The sensitivity and specificity for FNAB alone (162 patients) were 86% and 91%, respectively, and for FSx (494 patients) 79% and 99%, respectively. The routine use of FSx with diagnostic FNABs did not improve the accuracy over either test alone. Sensitivity, specificity, and accuracy were essentially unchanged when the use of FSx was limited to just atypical FNAB but dropped significantly when FSx was not used.

CONCLUSIONS

When results of FNAB and FSx are interpreted as benign or malignant, both are highly accurate predictors of malignancy. Routine use of FSx and FNAB does not improve the sensitivity or specificity in the detection of malignancy over that of either examination alone. FSx proved useful in determining the extent of operation only when results of the FNAB were atypical.

An analysis of fine-needle aspiration biopsy of the thyroid in children and adolescents

Fine-needle aspiration biopsy (FNAB) has proven safe and efficacious in the evaluation nodular thyroid disease in adults. Only one study has evaluated FNAB exclusively in children, for whom the prevalence of thyroid nodules and the probability of malignancy are different. In addition, no study has compared the accuracy of FNAB with that of other diagnostic procedures in the evaluation of thyroid nodules in children. The authors report the results of FNAB in 18 children evaluated for thyroid nodules between 1985 and 1994. The overall accuracy of FNAB was similar to that of other diagnostic procedures, including thyroid scintiscan and ultrasonography, but none of these was sufficiently accurate to be used as the sole predictor of malignancy. There were three false-negative biopsy results; this limited the overall accuracy and suggests that children with negative FNAB results should be monitored cautiously.

Large cystic/solid thyroid nodules: a potential false-negative fine-needle aspiration

BACKGROUND

False-negative fine-needle aspiration (FNA) biopsy results of thyroid nodules are of particular concern because they imply missed malignant lesions. The purpose of this study was to identify characteristics of thyroid nodules that may lead to false-negative cytologic interpretation after FNA.

METHODS

We reviewed 90 consecutive patients who underwent preoperative FNA of thyroid nodules followed by thyroid surgery during a period of 27 months, including their clinical data, type and size of thyroid nodule, FNA cytology results, and final pathology report of the surgical specimen.

RESULTS

Thyroid nodules that had the highest probability of malignancy were those that were large (3 cm or larger), cystic/solid, or large and cystic/solid. The overall false-negative rate for preoperative FNA was 11%. Large, cystic/solid, and thyroid nodules with both characteristics had false-negative rates of 17%, 25%, and 30%, respectively, compared with 0%, 9%, and 17% for small (less than 3 cm), solid, and solid nodules 3 cm or larger, respectively.

CONCLUSIONS

Because of the high prevalence of malignancy in thyroid nodules that are large (3 cm or larger), cystic/solid, or large and cystic/solid and the high false-negative rate of FNA in diagnosing these lesions, thyroid lobectomy for diagnosis should be strongly considered in these patients even when FNA cytologic finding is interpreted as benign.

The use of ultrasound-guided cutting-needle biopsy in the neck

Histological analysis of an abnormal neck mass has traditionally required an excision biopsy under general anaesthetic. We evaluated the safety and accuracy of a new spring loaded cutting-needle for obtaining tissues cores of neck masses under ultrasound (US) guidance. Sixty biopsies were performed on an outpatient basis under local anaesthesia in 52 patients referred with a neck mass. Patients ranged in age from 10 months to 89 years and masses varied in size from 5 mm to 5 cm. Fifty-eight of the 60 biopsies provided a diagnostic histological specimen. Of the remaining two patients, one required open biopsy and the other returned for a second needle biopsy. All five cases of lymphoma were correctly diagnosed on needle biopsy; in three cases full tumour sub-classification was possible but in two patients an open biopsy was subsequently required. In 49 patients the needle biopsy obviated the need for a surgical biopsy for diagnostic purposes, although in 12 cases a therapeutic excision biopsy was performed. Apart from one subclinical haematoma, visualized on US, there were no immediate or delayed complications. In all patients, the histological diagnosis was compatible with subsequent clinical, radiological, surgical or autopsy findings. Cutting-needle biopsy of neck masses under US guidance is an effective and safe procedure which should be considered before resorting to routine surgery.